Both scenario will surely help bitcoin succeed however, the most plausible one is the mass adoption first, regulations follow. Governments only regulate certain type of asset class/investments if it see that public attention towards it is high. If people already adopt bitcoin right before regulation, there's a solid foundation for survival, regulation only strengthens the masses' confidence about it. Whereas in the opposite scenario, no one would dare touch bitcoin if regulations and taxes are already in place; no one would take hefty profits and no one would be interested as it would seem like bitcoin is just like stocks and derivatives, only with a sassy name.