Is leaving a university to start a YouTube channel to invest logical?

Not particularly..... online earnings can fall off the cliff unbelievably fast, especially in the last few years when there's been lots of changes coming in.

YouTube has been particularly bad with the various "Adpocalypse" events taking down loads of YouTubers.... the 2018(?) change to making it so you needed 1000subs + 4000hrs a year of watchtime took out loads of YouTubers who had been monetised for years..... and that was followed a while later by the "Vox Adpocalypse" where a failing woke left-wing media company funded by NBC called Vox managed to take out a load of smaller YouTubers in their attempts to nail Steven Crowder + PewDiePie seemingly as revenge because they were having more success on there starting out as a "man in a shed" type operation than Vox were with millions in funding from a big media company.

https://www.youtube.com/watch?v=Uq3wyT6XpyY

https://www.youtube.com/watch?v=NQZ-mbYQgS0

https://www.youtube.com/watch?v=APV4tA-jkU4

Most people leave university (with a degree), get a job (even if it's flipping burgers).... then do YouTube in their spare time, using funds from the boring day job to bankroll their YouTube activities.... or some use their day job for their YouTube content, particularly if it's a skilled trade.

As stated, not a good idea.  there is no guarantee that your channel WILL make money, and not consistent money.  with a college degree, working in a field wher eyou have a regular income you are protected during those times when the channel income is growing or shrinking.  

That’s about the dumbest thing you could do. Even if your YouTube channel makes money, it certainly won’t be permanent. People will eventually get bored of it. A college degree will benefit you for the rest of your life.