Can't talk about aerobatics but I have an idea about biz jets. To keep it short I'll do it in a list.
-Ex airline pilots with 1000s of hours on jets
-Contacts in the industry
-Working for a biz jet company before becoming a pilot
-Luck
I know flying instructors who's first job was in corporate aviation on a turboprop and then they moved up to a jet.
Many many ways to get into it. Having contacts is a big one, especially for the small outfits.