The people who smoke dope aren’t necessarily dopes.

I hate to poop on New Jersey’s pot party, but I have a question: Why would anyone buy legal marijuana when the state is planning to place a $42-an-ounce tax on the stuff?

You probably heard that Jersey is about to legalize marijuana so that adults can buy it for recreational use. It’ll be just like booze, which anyone over 21 in the state can purchase. Only difference is that New Jersey doesn’t tax liquor as onerously as it will pot.

There’s a 12-cents-a-gallon tax on beer in Jersey and 85.7 cents a gallon on wine. Hard liquor is taxed at $5.50 a gallon.

But Trenton wants pot smokers to pay an extra $42 an ounce for the privilege of buying legal marijuana. Doesn’t the state have anyone working for it who knows anything about marketing a product and competitive pricing?

Keep in mind, people who don’t want to pay the liquor tax can’t really find someone with a moonshine still in a backyard and buy booze illegally. At least, they can’t find a still operator very easily — even in rural Jersey.

Sure, grandpa may be making some wine in his cellar. And crazy Uncle Lou might have received a beer-making kit for Christmas. But, by and large, there isn’t much of an underground business in spirits.

But marijuana sellers are all over the place. I don’t know where they are, and you probably don’t either. But people who want a joint knew how to get one long before Gov. Phil Murphy gave his OK.

Here’s my position on marijuana use, and it comes from previous columns I’ve written. (I didn’t just fall in line with the latest desperate taxation trend.)

I’ve written that I thought marijuana should be allowed for medical use. Anyone who didn’t agree with that, I felt, was inhumane and — I’ll say it — an idiot who never knew someone who was truly in pain.

And I wrote four years ago — without even a smirk — that pot use should be allowed near the Atlantic City casinos as a way to draw in business to that desperate city.

People laughed and thought I was joking.

Then, suddenly, Jersey decided it’s going to legalize pot smoking all over the state. My idea was radical a few years ago and now it’s quaint, even backward.

Back to the money issue.

The website PriceofWeed.com says that high-quality marijuana — the illegal kind — will set you back $400 an ounce in Neptune, NJ, and only $160 an ounce in Jackson, NJ.

So anyone who wants to ride on the Six Flags coasters should wait to get near the amusement park before making a purchase.

I don’t have any idea what the legal weed will sell for. But this much is clear: Whatever the price turns out to be, there will a $42-an-ounce tax tacked on.

Why would anybody buy the legal stuff? That’s especially true since having marijuana in your possession will be legal. At that sort of markup for the legal stuff, the street dealers are not only going to stay in business but also prosper.

So once pot becomes legal in New Jersey — and the state is insisting on its $42-an-ounce cut of the action — are the cops really going to haul anyone into court for having a few marijuana plants amongst the cucumbers and squash in a home garden?

I don’t think so. And I think Jersey is going to get some reefer madness once its marijuana tax scheme doesn’t work out quite as planned.