What do you mean "do not return value"? Is donating your computing power to helping cure disease a return of value?

From an investor perspective I have done only cursory research so double check everything I say for yourself. Gridcoin is PoS, so owning gridcoins can gain you more gridcoins at I believe a rate of 1.5% per year. As a business they have a lot of room for growth: the BOINC network is huge and only .5% of BOINC users are earning through gridcoin, meaning most people donating their computing power are either not earning coins for it or have a different way of getting paid, but I suspect most are just doing it to help academic research and are paid nothing. 

It's a pretty crowded space though, as I said at the top I have a lot of golem and I believe there are other competitors like iEX/SONM. I'm not going to personally invest money in it because of a few reasons:
1) the returns from PoS are lower than returns I get loaning other coins on exchanges
2) I can earn gridcoins by donating computing power so why do I need to buy them if I'm not doing PoS staking?
3) crowded space like I said.

That said I'm not a trader, I have no idea what the price will be in X time, and I only own a handful of different cryptos currently. I probably should invest some into gridcoin as a hedge against golem, but that's not a great reason to invest imo.

One additional update: by owning Gridcoins you are eligible for solo-crunching rather than pool mining. Since I owned no Gridcoins when I started this I just joined a pool because I read that is better when you have a balance under a few thousand gridcoins.