Sometimes you can service both. GitHub, Heroku, New Relic, CircleCI, are all examples that serve 6 and 7 figure contracts while also supporting tiny 1-person contracts too.
Did these companies start doing both or only after getting investment? It's a genuine question, I don't know. I'm guessing you need to reach a certain mass to be able to do real Enterprise sales.
Github self-funded through $9 to ~$250 a month accounts while they were building their behind-the-firewall product which they sell to enterprises.
You need to have a certain mass to be able to sell six figure a year deals to a true Enterprise. I'd ballpark that mass as 90 lbs or so. They'd hire a software engineer who was 110 lbs soaking wet for $100k a year though, right? So clearly that engineer succeeded in an enterprise sales process at least once.
People tell me that that's different, but it is and it isn't. I closed my first (small) enterprise deal for AR, for a consortium of over a dozen hospitals (we got a tiny sliver of their appointments business), back when our run rate was below $2k a month. I felt pretty terrified about being on the phone with a VP they had around just to talk about HIPAA compliance, but no part of that conversation was a blocker to them doing the deal. (Long story short: I had done my homework on HIPAA and demonstrated that I understood what I was promising them. I then delivered it. The end.)
And not coincidentally, they all target the same person - the developer. You can't generalize about selling to all people based on this specific persona.