Offered founding engineer, funded. I will not promote.

I'm in a tricky situation where I was offered the role of founding engineer in a well-funded startup. The MVP is a vibe-coded mess made by a non-tech founder, which is not yet deployed and was used as a demo. I want to do a complete rewrite in order to build a maintainable and scalable product. I'm expected to work full-time and manage everything technical regarding the project, including and not limited to: -Backend implementation: Design & architecture, performance and maintenance. Every technical decision. -Frontend: One admin, one client facing application. Maintenance and debugging of the existing vibe coded mess - -Infrastructure: CI/CD pipelines, Docker Deployments Databases Scaling Monitoring, Prevention of downtime Production incidents Security-related technical issues Server / infrastructure problems Obviously an extremely demanding role with huge work loads. The difficulty of the decision comes to the fact that my current position is threatened due to financial difficulties for the company. This means that I might be out in a very difficult job market with little room for negotiation and benefits. The offer comes with the benefit of a standard job contract with guaranteed salary which will be a slight raise from my current position, as well as 2% equity. The product is interesting and has good chances to succeed, however field is something out of my interests domain. Apart from the no-risk opportunity, I love writing code and can pull this off. I've already been in a similar position, albeit with more manpower behind it. Am I crazy I'm considering it? Given I'll be building the whole thing by myself (or if I manage to convince founder and bring another dev from my network to ease up things), is it naive & greedy to negotiate a better equity and co-founder title? Should I just focus on building something myself?