Here's the thing about career politicians: they're good at what they do. At least in that they know what they're doing, how the system works, etc. When they're not effective, at least in a system that's not been gerrymandered to hell and gone, they get replaced.
Does anyone ever say they're tired of plumbers who've been plumbers their whole lives and so then go out and hire an electrician to fix their water main? Hell, that'd still be a better fit than Trump as POTUS. At least an electrician's been on construction site before and knows what plumbing is. Anyway, some degree of public service should be required before becoming POTUS. The whole, "Yes, Little Johnny, you really can grow up to be President" sure as fuck wasn't supposed to work this way.
On the other hand, there are people like Al Franken who never served. But when he got elected he put his nose to the grindstone and worked his ass off to learn the job. So it is possible for a neophyte to learn on the job in politics provided they have the willingness to work, listen, learn, and have the best interests of their constituents at heart. Unfortunately, Trump displays none of that as he waddles off to his 17 day vacation after demanding the entire Senate stay in Washington.