The startup life means there's a lot of legal and financial roiling going on at the management level that Employee #1 and below aren't allowed to see.
Probably a visa issue. Maybe a money issue (they don't dare admit that to any outsider, and employees are outsiders, so get the polite happy faced response management gives the rest of the world). Probably the all-too-typical inexperienced management issue most startups have.
When you choose to join a startup, you have to have a strong tolerance for surprises, some good, many bad. ALL of them are nice-seeming guys (nobody'd work for them otherwise). ALL of them have cool-sounding projects (will they work? Will they step on Big Legal's toes and die in deposition-induced agony? Will another 100 companies jump on the bandwagon before you can get it out there?)
It's a VC-self-serving myth that startups are succeeding at an increasing rate. See: http://fivethirtyeight.com/features/corporate-america-hasnt-... for the actual stats.
Keep in mind that chasing startup dreams may not be healthy for family life, especially given that the failure rate for startups has been increasing, not decreasing.
Of course, it's always made to sound like success is just around the corner, but your most recent experience should give you a good idea whether your family's risk tolerance makes it worth it to you and those you love. The odds of dreaming turning from a bunch of extreme hidden hard work into extreme hidden burned-out failure are high. The startup world's only prescription for that is that you rest up a bit, then do it again.
There's a reason some people take the corporate jobs, save up, and only then follow their dreams.
Too many people are wasting their precious youth following the "fail early, fail often" mantra that is counterintuitive for a reason.
VCs make their money on the ones that succeed. The ones that fail don't cost VCs all that much, once you start counting actual funded startups that have passed all due dilligence and cashed the check. It's hard to filter out all those who are really only braging about funding on the way, because they've got to be convincing about already having it to have any chance of getting it.
But a steep price is being paid in wasted best years caused by startup failures. I count as failures, even these smaller "pivots" such as one where an employee is let go because different talents are needed (their stated reason to you). You wasted your time? No skin off their noses, they get to be the nice guy to somebody else they can use.
The startup world's harm is as cruel as any harm the corporate world can do. The startup world is just far less honest about the harm that it does to individual startup employees, preferring to say whatever they need to, keeping everybody's dreams alive until they absolutely can't anymore.