What stopped me from buying flagship phones is the repair costs for phones are far too expensive in relationship to the value of the phone. Results will vary, but waterproofing usually diminishes after a repair.
Eh... get protection plan, or trade up every year for big discount on the next flagship. Or with AT&T plans you are getting a "free" phone fairly often if you don't intend to leave the carrier for a few years (most people wont). The parent comment you replied to makes some assumptions that you have to spend full price all at once every year which is false. Also, there's almost always a deep discount on Pixel phones around most holidays.
And if you truly are ultra budget $300 phone guy then sure this doesn't apply to you.
I am not the right market for flagship phones because I don't have thousands of dollars to put towards disposable income, but I would expect a premium phone to come with a premium warranty and repair service... Do they typically not?