A $5k bike will fall apart way more quickly than a $1k to $2k bike. The only reason to get a $5k bike is if you are trying to win a race and have other people to do the maintenance for you. The lower end (but not absolute cheapest) parts are generally more reliable since they aren't nearly as weight optimized.
Maybe? I am not really sold on bikes falling apart. They all have consumables. It’s no different than a car. Sure there are some hyper specific frame styles, thinking of you tri bikes, but beyond that they don’t feel less repairable.
Yes, bikes built with race equipment need to be maintained like race equipment. Don't buy a $5k bike (or a Porsche) if you are going to complain about maintenance intervals.
