I want to buy from the Frictional Games Store but it seems to be a bad investment

[mansarde]

It usually boils down to this: Buy it from the place that's the most convenient for you or compatible with your principles/beliefs.

I hold much respect for developers working Independently and doing what they do, so if the option is available I'll get the game directly from the devs.

Since you can do that, why don't you just go and do exactly that?
Hint: http://store.frictionalgames.com/

Edit: In case I misunderstood and you already knew, then you have my apologies, just wanting to help.