As the only tech cofounder, should I quit my startup?

Since you're young take it as a valuable lesson - don't work until your agreement is in writing. If your potential partners do not have the basic funds/access/knowledge on how to form legal entities and legally-binding obligations they have an extremely small chance of success to begin with.

From what you described, it feels like quite a dysfunctional team. Investors will be able to smell that, which will affect the chances of getting an investment as they usually invest in the team rather than the idea itself. But even if the funding comes through, the team is breaking apart, so that means it may fail and the equity will be rendered valueless.

It sounds to me that you made up your mind of leaving and you are just thinking about how to get a return on your time. Since it's a tech startup, it's heavily relying on technical expertise, so you have all the negotiating leverage as the CTO. Without you, there is no product and mostly likely no funding that will come through as a result. Not sure what the terms were when you first got onboard, but use that to your advantage to renegotiate and have a real talk ASAP with the CEO and get something in writing to make sure you either get compensated for your worth when funding comes through, either in salary and/or equity, or you get paid partially right now in case the funding never comes through. You don't need to come across threatening, but you can most certainly make it clear that you need tangible reassurance of getting compensated and other changes that you'd like to see in this relationship going forward. Don't wait. Have that real talk now with brutal honesty. That's the only way it can get better.