Crypto space is too dynamic. Timing is everything. I was mining Bytom with GPU from the very beginning of mainnet. Now difficulty is higher and I'm holding long term what I mined. Did You do the same with FPGA?
As I like to be diversified (CPU, GPU, ASIC, trading), I would enter FPGA mining if I see realized plans of having number of developers interested, publishing algos fast enough and competing with fees over miners.