I know a few people who gave up their licenses after 5 years of unemployment simply due to the fact of high loan repayments and high costs of ME/IR revalidation. They simply reached a point in their new careers that it wasn't really worth the money, time and effort anymore to keep the license current. Most of them came out of flight school in 2009 and gave up their licenses around 2013... just before the markets started to pickup again. It's a shame, but it is just the way it is in the end.
They have good careers now in different sectors.
So to answer the question. Yes, there are quite a few who never made it to the airlines but the people I know all gave up at some point. A few friends who were without jobs for years but always stayed current are now finally getting jobs in the airlines.