It’s repair costs. Some manufacturers have scant parts availability… manufacturing processes that work for them but impact the ability to repair. Just because you can design and build a vehicle doesn’t mean you understand anything beyond the initial purchase.
Just watch wham bam teslacam and look at the repair costs for smaller impacts. You could buy a new ICE car for some of them.
If you just want something to work on as a hobby go for it. But beware it is probably a money pit.