I was in a similar boat. I abandoned a potentially very lucrative startup because the owner (my friend's brother) insisted on using Websphere and all the associated apps (he was a former IBMer). There came a point where some misconfiguration occurred when attempting to restore a previous version of the application after that point nothing worked. I tried for days on end to fix the problems but nothing would compile without massive errors. The piles and piles of cruft that Websphere added did nothing but obscure the real source of the issue. Eventually I gave up and said screw it and left.

The startup was already on its last legs at that point, as I was the only active developer since the other developer I worked with had already left after getting fed up for other reasons. After I left the startup limped along for a while but as far as I can tell was abandoned. If they had just used a more sane environment I could have easily developed the entire thing myself as it wasn't anything more complicated than a straightforward CMS + payments. I still kick myself for not making a better case for a more sane environment but I was wet behind the ears at the time and I didn't trust my instincts in the face of guys with masters degrees and X years at IBM and other top companies. I know better now.