Series A job offer in the 200k range (currently working for a little over half at a big company) worth it? I will not promote.

​ Title says most. Job offer is great on paper and im into the work but not sure if the salary is worth the lack of security. They are in the process of upscaling and a large hiring effort as they have quite a few contracts but their manpower is a bit limiting. They have quite a bit of capital from what I can tell which leads me to beleive its safer than one would expect but they call themselves series A and are a good few years old (I'm not well versed on terminology but from what I can glean this may be a bad sign?) Any advice helps. I really like the mission and people but I don't want to leave my very stable job for an unexpectedly short term more enjoyable and higher paying one.