(If you own your own jet, it's always where you want it, you can decorate it the way you want, and you can leave your stuff in its bedroom and living room. It's like having a pied-à-terre in a city instead of renting a hotel room each time you visit.)
The operating cost of a jet that's actually ready at your beck and call also includes its crew. That's maybe another $200k/year, or 4% annual interest on $5M principal, so add another ~$5M to the wealth required in order not to go broke this way. (Disclaimer: I unfortunately have neither the practical experience nor finance knowledge to know if I've used the right fully burdened labor costs and multiplier, but it's going to be in that ballpark.)