I read a book about watchmaking, the author said it's like the greatest temptation in the world and human history to open and do shits about a watch by yourself. People who have absolutely zero knowledge about horology will still think they can fix a watch, or swap a movement. And that's why the watchmakers survive - by fixing the shit these people started and couldn't finish.
My friend used to work at a bicycle shop. They used to give a free spoke wrench to anyone who bought a new bike.
They knew everyone would try to "adjust" their spokes and the bike would be back in to be fixed shortly after, lol.
That said, while I wouldn't attempt a disassembly and service on a gen chronograph (a man's got to know his limitations), starting out with simple things is how we get to be "watchmakers." I started with a simple replacement of a quartz movement, then to the build of a Raffles Datejust, and am now building watches from the ground up, servicing movements, and creating dials from scratch.
Simple things (and replacing a movement is a fairly simple job, if you're slow and methodical about it) are the stepping stones to bigger things. I would think that most watchmakers in the field today didn't receive extensive formal training. Many of them started out apprenticing at a watch shop, watching and learning from an established watchmaker. You Tube and the internet (including this forum and others like it) are today's version of a master/apprentice relationship.
Paying someone $200 to work on a $200 watch adds up...it's better to make $20 mistakes 2 or 3 times before it's all sorted and running smoothly.