It's not that hypothetical as I've been in this with young companies where we were deciding where to launch first (for beta or actual launches). Granted there was nothing then precluding EU users in those times, in fact we preferred it to help w/ i18n vetting. Nowadays, I'd just as soon leave EU countries off of the select box on my signup form, and not worry about GPDR compliance (again, even though I am probably compliant and believe in the spirit of the rules).
And as of the earlier arguments like “no loss” or “competition would step up” - look how few EU tech companies there are. There’s a reason for that.
The armchair commenters here aren’t EU business people, and it shows. Around here, GPDR is considered a disaster, in the usual style of EU’s heavy-handed, poorly thought-out regulations. It adds so much bureaucracy and expenses - even for companies that do nothing shady - that it is absurd.