i dont think michael manring or jhon patitucci or michael league ever made that much money from playing bass , making a living /career on YT and making a living being a musician is 2 separate things .
Davide makes a living doing videos that features a bass guitar
the guys named above (just few names but there are thousand of them ) make money playing bass that are features in video (videos being a secondary way of get their names out there .
Before youtube people used to buy magazines to discover new bass player, new bands, new sound ....,
so for a second just swap youtube for a bass mag for ex
so ..... Davide writes magazines about bass and he makes a great living .(probably better then the people featured in the magazine
The people featured in the magazine , thats what i care about no who write the magazine.
again personal opinion .