Sure, but if you are planning to go from SME to enterprise you need to think strategically for the long term. You'll probably need to have more developers to deal with the complexities and hand-holding you've touched on (auth is just one of the issues and not even the most complex) and probably non-technical roles for all the compliance and so on.
The danger of landing just one or two "whales" is that you bend your product backwards for these clients, but without thinking through the TCO it can cost you more in the long run and put your business in more jeopardy than when you rely on a few hundred SMEs.
The danger of landing just one or two "whales" is that you bend your product backwards for these clients, but without thinking through the TCO it can cost you more in the long run and put your business in more jeopardy than when you rely on a few hundred SMEs.