Mark Fischbach recently had an existential crisis, ranting that he had squandered his life playing video games. His lamentations, which he filmed and posted on YouTube three months shy of his 30th birthday, were viewed nearly one million times.

Insanely, that number is rather on the low side for Mr. Fischbach, who is better known as Markiplier to his more than 24 million followers on YouTube and his 12 million followers on Twitter, where he refers to himself as a “Professional Screamer.” In 2012, he dropped out of a biomedical engineering program at the University of Cincinnati and started to record himself playing games and going about his life; since then, the clips have been watched more than 11 billion times. His most popular video, a review of the game “Five Nights at Freddy’s,” has been seen 75 million times. Even a clip about his wisdom teeth removal exceeded 3.7 million.

According to Forbes, Mr. Fischbach is YouTube’s sixth-highest-paid personality, earning $17.5 million last year. He also makes money offline. In 2017 and 2018, he spent months traveling the United States, Europe and Australia, performing in an improv comedy tour. And he became partners with another YouTube personality, known as Jacksepticeye, to start Cloak, a clothing brand for gamers, which sells $80 hoodies and $70 sweats.

We caught up in May, after he drove his Tesla Model X from his home in Los Angeles to Austin. There, he planned to spend several weeks preparing and filming “A Heist With Markiplier,” a film funded by YouTube.