He's mentioned considering making let's play a career at least once that's been documented - on a stream from 2017:
He specified that it would have to actually seem viable financially before he'd attempt it though. But yeah, Slowbeef desperately wants to be a famous eceleb.
In my opinion the Retsupurae content he made with Diabetus was excellent and some of the most genuinely funny content on Youtube. Maybe they couldn't have made a career out of it but they could have stayed making great content together, it's sad that they don't.