How easy is it to make a decision that guarantees you'll be a millionaire in just a couple months?

Harder than you think, actually.

But for Austin Rivers, becoming the latest one-and-done out of Duke is a no-brainer, although it is met with uncertainty from some. Rivers made it official though, as he and Duke publicly announced that he'll be entering the upcoming NBA Draft.

Rivers is far from a rarity in a one-and-done world. With recent players like Kyrie Irving and Kevin Durant becoming instant stars, it makes sense to think, "Hey, I can do that too."

Over the past two seasons, the Celtics have gone from drafting a one-and-done in Texas' Avery Bradley, to two four-year NCAA players in Purdue's JaJuan Johnson and E'Twaun Moore.

With that in mind, it's clear that age/class isn't first on the Celtics' scouting report.

"I've always said the one-and-dones who haven't made it would have been four-year players and hadn't made it," Doc Rivers said, fielding questions about his son's decision. "Usually it's the same way when you have guys that went two years and three years and don't do well in the league. It turns out whether you're a player or not. I don't think it's much more complicated than that."

Maybe not, but timing is everything, isn't it? Bradley's decision to enter the draft isn't one he regrets, but it's safe to say the NBA world was a major smack in the face upon arrival for the now second-year guard who is just starting to come into his own.

"I just felt like I was ready to learn more about the game," Bradley told CelticsBlog of his early-entrance decision. "So me and my family decided that it was best for me to enter my name into the draft. At least try it out, and I ended up keeping my name in."

Johnson was faced with the same decision as Bradley last season.

"I actually declared my junior year, worked out with a couple teams before the deadline," he told CelticsBlog. "And I decided to go back to school. I just thought the next year I could put myself in a better position to help myself, and also I wanted to finish up with the people I came with. So those were my biggest two things."

The decision to go back was obviously a big one for Johnson.

"It was tough," he said. "I didn't make my mind up until probably like the day before the deadline (April 10). I just knew that whatever decision I made I had to live with it and just move forward."

Bradley's decision to go forth with the draft proved beneficial in some respects, and detrimental in others. He had officially made it. The NBA. The Bright Lights. This was where the stars come out to play. It was a long time coming and Bradley was ready to take it on. Or was he?

"The pros about entering the NBA is, like I said, you get a chance to play at the highest level, and not only that you get a chance to learn more about basketball because it's completely different," Bradley said. "You look at the game completely different once you get to the NBA.

"But the cons are I was so young, I was kind of behind. But at the same time the pros was I still had room to learn, room to improve. That's just a few of them. But, you know, there's definitely cons. There's going to be cons for everybody, even a four-year player."

And we'll get to the cons of a four-year player in a minute, but more on Bradley - and the gift-and-the-curse nature of not only coming out so young, but onto a team like the Celtics with such established future Hall of Fame players, and a coach that loves his vets.

"Not to take anything away from any other NBA teams," Bradley said, "but Ray Allen, Paul Pierce - I was like, ‘Dang, these guys are good.'"

Were they great teachers to learn from? Of course. But they're also a bit intimidating.

"Definitely being a young guy it makes you hesitant," Bradley said. "Especially because I was hurt so I didn't get a chance to gain confidence in training camp or get a feel for the game. It was kind of tough for me."

Bradley didn't get that confidence or sense of belonging in the NBA until his trip to the D-League last season. It was then when he came back knowing he belonged.

"When you're not playing and you're injured, being young, sometimes you're like, ‘Dang, am I good enough to be in the NBA? Did I make the right decision?' But going in the D-League I got to see that, ‘Yeah, I am as good as I thought I was.'"

JaJuan Johnson hasn't made that trip up north to Maine this season, mainly because of how thin the Celtics have been at the power forward and center position.

For that reason, he's spent a lot of the season riding the pine, and learning from the guys in front of him. Had he entered the draft last season as a "late first, early second" pick according to his projections, maybe he lands on a different team with a bigger role at this point in his career.

Like Bradley said, there are still cons to a four-year player. Johnson would agree.

"When you stay longer, scouts and GM's just dissect you even more," Johnson said. "I think in a way almost, staying four years I don't want to say it kind of hurts you but in a way it does just because if you stay this long then it's like, ‘What is it that's [wrong]?' If you look at recent drafts, it seems like the younger players have been going higher.

"I mean, you can't knock it. They have a successful freshman year, they make it kind of hard, you almost have to go now. That [same kind of year] is not guaranteed, so you got to do what you got to do."

But Johnson is in no way upset at the decision that allowed him to truly fulfill his NCAA goals.

"[Staying] helped a little bit," he said of his draft stock. "I think just the pros are definitely just getting my degree; I had a good senior year. So there were a lot of things that were good, so I was happy with my decision. Obviously [breaking records] is great. Getting your jersey retired [at Purdue] and stuff like that is something that will always be there, so that's pretty cool."

There will be no jersey retirement ceremony for Austin Rivers at Duke, but according to Doc, it was pretty much understood early on what Austin's goals were.

"I think he's always wanted to be an NBA player," Rivers said. "I don't think he ever hid that. Coach K (Krzyzewski), one of the things he said was, ‘We recruited him as a one-and-done.' The same way they recruited Kyrie [Irving]. That was part of what they talked to him about a lot before he got there. But he still almost stayed because he enjoyed it. He enjoyed Coach K."

Rivers would never publicly speak out against his own son's decision, and clearly supports the one that was made, but don't think that it didn't come with a stern warning: this won't be easy.

"I'm happy for him. I really am," Rivers said. "We had input in it. We let him have more input in it, honestly. I'm just happy that he's kind of at peace, he's made his decision, and now he has to get ready for us."

Whether a one-and-done or four-year player, that process is tough. Bradley and Johnson can tell him that.