Have sold to a lot of governments and large contractors. I wouldn't say its a death sentence, just different business model than most startups. Government and large orgs that send out RFPs are essentially asking for a product/service to be made and maintained specifically for them. Unless your essentially in the consulting business, its rarely worthwhile for a normal startup as it eats A LOT of time for a single customer. Government can be very lucrative if you can find the right niche but its always exceedingly painful and one of the governments favorite pastimes is completely 180ing requirements right after you complete them.
Problem here to not underestimate is that if you are not experienced in RFPs you will spend 10x to 20x the time than someone that has experience int these processes, and then there is a real risk that you optimistically misinterpreted some qualification criteria that disqualifies you in the process. So if you have done this before, do it. If have to do it for the first time, you want to consult someone who has walked the path.
