Startup consist of 2 founders, they were at this for the last year+ - building a B2B product.
1. industry expert / sales
2. data scientist / cto (part-time)
One of them is my friend.
I joined 3 months ago, helped accelerated the growth - research, sales support, marketing, and products.
However I did not know enough about the industry (which I caught up understanding through reading; [experience needed]) nor I have data science expertise.
Last 3 months, we spoken to clients. Soon to closing early BETA deals. Marketing materials developed. Prior, we did not have any of this.
We still will not see substantial revenue until the next 3 months.
So for 6+ months, with little or no income. I am okay for now since I still live with my family and have savings. However risk is being incurred...
Option A: Look for a product manager role at another startup.
Option B: Stay, if 10%+ equity? No income for 6+ months?
EDIT Option C: Do some freelance gig till then. (Not a big fan of this one.)
FYI, I am a self-taught developer, designer, and sales & marketing. Jack of all trades, master of none (depends on who am I talking to). Just graduated Masters a few years ago, previously worked in financial industry. My aspiration is to be an entrepreneur myself, tried a few things before, hard time finding a team.
Now to me, if I were one of the founders, the most critical question on my mind would [hopefully] not be, how much value have I put into the company in the past six months versus how much you have put in. The critical question on my mind [hopefully] would be how much value you bring to the company in the future. Maybe it's 10% - in which case I would consider looking for someone else. What I would want [hopefully] is someone with the potential to exponentially increase the value of the company and therefore who is worth a founder's share. The idea is that a new company is born the day you come onboard.
Yeah it's a little crazy, but a startup is about big risks and big rewards, not little ones. 10% is fine for a lifestyle business with a proven business model and where the founders bring irreplaceable assets [big capital or licensed access to a restricted market]. But lets face it, though most people probably cannot grow and run a company, there are a substantial number who can unless you're Wolfram Research.
Anyway, I don't if that's advice good bad or indifferent, but good luck.
[1] If you walk away with nothing financial from this deal, it's still pretty much identical to the most likely outcome had you been granted equity six months ago. Startups usually fail.