Wow! While directionally correct, there are several comments that are just hyperbole, or generally incorrect. If one sprayed 10 coats of base in a basecoat/clearcoat system you would have cracking paint and a very dull and non-robust finish, at a minimum. One coat systems, different story. Your typical cut & finish process (say with products similar to Meguiar's 105/205 2 step) removes around 5 microns of clearcoat. A typical "professional" wet sand with 2000 initially then finishing with 3000, and then a 2 step would remove around 12 microns total. Again, many variables exist here, but these are values for folks that "know what they are doing".
On a side note, many of the cars with peeling paint back in the 80's were a result of OEM's not understanding UV degradation to the e-coat layer without an UV "protective" layer in the primer or top coat. Blue, and other colors prone to UV absorption were the most problematic.
Not wanting to get into a p***ing contest, I'm not going to comment further on this thread. Most of my 35+ years in the automotive industry (majority in Paint Operations) makes me a bit OCD regarding these types of discussions. Getting back on topic, yes I am older, and also do my own detailing Lol. Take care.