You mention burned out. Could you not take a break away for bit? You also mentioned you spent a considerable amount of time building the base, thus I'm assuming you have put in more time and effort than the others. Why not try and take a week or a month away (either doing something else or vacation) and see if you feel any different? You will get a chance to think and solidify your decision to leave.

Could you maybe change roles in the company? Do something that brings back the energy you once had towards it?

However, by the tone in your first 2 sentences it might be too late. It sounds like you have already made the decision to leave and do not believe in the company at all. In which case, the others might not even want you there anymore anyway and I can't blame them.