When it’s less then 20 dollars in parts and I know it’ll be done right yes I’d probably do it my self. It would cost 4-5 times more in Uber’s to get to and from the dealer then the parts cost. Doing the head gasket shouldn’t void warranty and it would be hard to prove a head gasket changed caused bearing failure.
Honestly working in the trade for a while, yes there are good tech. But there are a lot of terrible ones as well, if it’s something cheap, simple and quick... I’d rather just do it my self. Warranty isn’t free no but you pay for a lot of stuff you never use or hope to never use, it’s just the cost of having stuff I suppose.