Bit of a tough spot you're in Weljo2001. A responsible 26 yr old will have, I'm sure, taken your viewpoint into consideration.
When the "love bug" bites...well, you know...
Perhaps in the time it takes for him to clean out the garage and driveway
it'll have been enough time for the initial "cool down" process to take place.
Giving way to reason.
When my little bro was 18 he decided he wanted to go into debt and buy a Corvette. After a little discussion I found I had him pinned against the wall, ready to strike him, before I realized what I was doing.
It's funny how we can react when trying to "protect" a loved one from making a "bad" choice.
He made his own choice in the end, it wasn't a "Vette".
Don't envy your position in this Weljo2001.
Cooler heads will prevail.