The fact that they're offering you 2% for equal work/risk (after all, you lose just as much as they do if it fails) says more about them than whatever idea they're pursuing. I'd walk away.
They don't respect you at all and they're a completely lost cause. They're likely to screw you over or replace you at the first opportunity and blame you for any failures.
Two percent is insulting for the sole tech guy on a team of three. Even if they had an absolutely BRILLIANT idea and SUBSTANTIAL experience in the given industry.
I'm not sure what you're basing your statements on. But it sounds like you've gotten a very bad deal in the past. Or, you've had no deals in the past....
Well, okay, if we're going to make ASSumptions:
Maybe you're just sensitive to this situation because you are ALSO trying to get some poor schmuck to take 2% equity and no salary to implement YOUR big business idea, which is all you have to contribute to the venture? Or maybe you're a hacker that took 2% equity for implementing someone else's idea and you're trying to rationalize your empyty bank account and minimize the cognitive dissonance for yourself?
I'm going to ASSume there is something in YOUR past that makes you unable to hear the fire alarm bells and see what a bad freaking deal the OP is being offered.
We can argue about how much the superstar VP of marketing is worth, but we both know that the question doesn't come up if the first few tech guys don't hit a home run.
Often the "first few tech guys" don't have to do much more than create a working prototype.
It's extremely common (I'd venture to guess 80+% of the time) that the product that is launched is substantially different than the original concept. So, the initial coders are there to help prove the viability of the idea, not always to write 100% production-ready code.
As to the difference between the initial product and the initial launch, that's just as true of the idea as the code.
In fact, experience with the prototype and its development is what reveals what the viable idea actually is.
If the difference between the prototype and the product is large, the prototype development clearly had huge value, and it was largely due to the "tech guy".
If it's not large, the relative contribution of the tech guy ranges from secretarial to huge, depending on the idea.