I'm not at all worried about people 'catching on to us' or 'FIRE going mainstream' as we're bombarded by materialism and decadence ALL THE TIME - now more than ever. If Your Money or Your Life (1992) and The Millionaire Next Door (1995) didn't move the needle for 99% of the population, a couple of USA Today or Money magazine articles aren't going to.
I had lots of co-workers who asked me about FI over the last 25 years, and I shared the LBYM tenets (largely from the books above) and told them it was "simple, but not easy." A few of them changed their behavior for a few weeks or months, but I didn't convert a single person! Almost anyone CAN do it, but few choose to.
DW and I have an above average nest egg. We just got done recycling clothes hangers, most of my friends would think that's crazy.
This community is still (happy) outliers...