A bird in the hand was worth two in the bush is an old proverb meaning it is better to stick with something you already have rather than something you may never get.
I was in this situation a few years ago. I had worked at the same place for a lot of years trying to do a great job and really did love the jobs for many years. However, since times have changed and contract jobs were slowly eroding with pay ($5 less per hour) and time cuts (less than 40 hours per week), less benefits and I had some other reason I that are beyond the scope of this article It was a contract job so you have to expect this to happen. I decided that this was the time for change.
Anyway, I took the chance of leaving a job for another in a completely different area hoping area. That job went fairly well and I was thankful I had changed jobs. It was a completely different environment and the bosses were outstanding. I would love to have them as bosses again both on the civilian and government side and that cannot be said for many but they were fair and seem to have it mostly together especially the one I worked under. He was such a great person. In the end the contract was lost and so I became unemployed. I did not get a job for the long haul which was what I intended but got to work for some great people that I will never forget. So would I do it again. Yes, I would.