If the problem was solely the devaluation of FUN token we would be fine.
In fact, the devaluation of the FUN token is no small factor. At least because of it, there is no point in locking FUN tokens on the freebitcoin site, especially for a long period. For example, if you bought FUN tokens a year ago and locked them for 360 days, this investment would be unprofitable for you now.
Personally, I invested in FUN token aware that it was unlikely to be able to maintain its price along the time, because staking rewards are too high (up to 25% yearly), while there is low demand for the token in crypto market.
The most attractive feature of the investment was the increased interest rate paid over Bitcoin balance on users' personal freebitco.in accounts. This way, acquiring FUN would be still a good idea. Not because FUN itself, but due to the implicit benefits which came with FUN purchase.
It was supposed to be a profitable investment considering you had a large Bitcoin bankroll, and considering freebitco.in was a solid and reputable platform in crypto industry since 2013 or so. That was the main idea. However, things started getting too unstable there and it's not safe to keep BTC deposited at the platform anymore. If the site was safe like before, FUN could remain on the current cheap price, but the investment would be still profitable through BTC interest income for users with large bankrolls.