I don't (yet) have personal experience with this, but I've been researching it recently. If you are renting and sub-letting without the knowledge of the owner, you do risk the wrath of the landlord. If you are upfront about what you want to do, however, you can still talk some landlords into allowing you to do this. Most will not, but you only need one to say yes (ultimately more, if you want to go big).
There is definitely good cash to be made, assuming you pick the right area for this. I know of someone in Southern California is doing very well at this - he makes about $2k per month for each unit (that's net, not gross). And he has multiple units. He has bought several for himself, but most of them he is just renting and then subletting. I heard a podcast interview with him, and it sounds like the only thing he does personally is handle the online guest interaction - he hires people to do the cleaning and check-ins.
There are some courses on Udemy that teach you how to do this. I'm going through two of them. One is full of, IMO, shady tactics that probably work, but also might get you evicted. And the other one is pretty good, at least so far.
Bigger pockets has a forum dedicated to short term rentals that may be of interest.
https://www.biggerpockets.com/forums/530-short-term-and-vacation-rental-discussion