But as an insider, you have the ability to uniquely gauge whether this is an "average" startup, or one where truly thoughtful, innovative, honest, humble people are working hard for a dream that, from your vantage point, has a good chance of panning out, even modestly.
I will say that your $60k compensation isn't a good sign, though. It signals that the engineers they've hired either (1) are great engineers and they really, really believe in the future of the company, or (2) aren't that great. You can probably gauge which is the case for yourself, but across all low-paying startups, (1) would be a very rare case, and (2) would be far more likely.
The road to hell is paved with good intentions, as they say, but that road is build with some really solid engineering (it being so hot there and all), and we only really hear about the successful exits which reeks of survivor bias. The well run companies just fade away in our collective consciousness. I can name Uber and Lyft off the top of my head, no problem, but their defunct competitors? I'd have to look them up to name more than... Flywheel, I think it was?
Startups are high risk, especially if you have all your eggs in 1 basket. Whether it's reasonable to take the risk depends on data points that only you can ascertain.
The hard part is being honest with yourself. If you've invested 4 years into this job, you surely have emotional attachments to it that transcend economics. Feelings of loyalty are good and normal. One key question to ask is how much loyalty do the founders feel to you? Would it be hard for them to replace you? Do they treat you with respect and camaraderie or like a machine that produces algorithms? Are they competent, inspiring people that you learn from, or "idea guys" who are good at pitching but not much else? If you were the CEO, would you hire them?
Just a few of the questions I would ask myself in your shoes.