I am a start-up employee and it is almost 4 years now and it seems like the product might not scale up as expected and it would probably not be a unicorn or a 10x and might not even re-cover the VC investment. What should the career path for a founding employee be?
This is the reason you work for a startup in the first place. It's a gig where you get to play with cool tech and VC money, then get spit out sideways onto the job market when they invariably have to lay off the whole team. The "consequence" is that you get a free pass to look for another gig that pays better without the stigma of having job hopped.
Startups, from an employee standpoint, are not about getting rich off of the company succeeding. That won't happen. They're about building your skills in a fun environment, socking away as much cash as possible along the way, and leveling up your value by burning through a bunch of fun, hopeless companies in a short period of time.
The fact that it took this one 4 years to cycle itself is actually the only downside I can see here. Everything else is what you signed up for (whether you realized you were signing up for it or not).
Initially I thought you were asking how do you get another job, but after reading this again I think you are trying to figure out more so if you should found something yourself or is it smarter to join another startup or enterprise etc.
Career paths are not a common thing in startups as the structures are mostly flat and in general you get rewarded for just doing, and rarely are you on a career path or career development plan. So my answer is this. If you have a passion to be a founder and have an idea or two, start now, be a founder, look for a co-founder with your passion but complementary skills. If you are unsure or aren't interested in the startup path in terms of being a founder, find either another startup to join or start applying for more traditional enterprise technology (assuming you are in dev) roles.
Startups fail all the time. If you don't believe in it anymore just move on now, if you think there is still a way to be successful stick around and give it a longer try, if it still fails move on.
Don't believe the tech echo chamber that makes everyone believe there are only successful startups out there. There is a reason we use the word "unicorn" for very successful ones.
Startups, from an employee standpoint, are not about getting rich off of the company succeeding. That won't happen. They're about building your skills in a fun environment, socking away as much cash as possible along the way, and leveling up your value by burning through a bunch of fun, hopeless companies in a short period of time.
The fact that it took this one 4 years to cycle itself is actually the only downside I can see here. Everything else is what you signed up for (whether you realized you were signing up for it or not).
Now go out and double your salary.