I found the first one to be boring by comparison whereas I really liked Borderlands 2. Might do the same thing to you. Give the first one another chance and if you're not enjoying it that much (which I expect), try out the second one. It's a lot better in my opinion. The Pre-Sequel is basically what, for example, Arkham Origins was to Arkham City. A good but rather uninspired sequel to a great game that's only worth it if you really liked its predecessor.
At any rate, I don't think you should "waste" the $18 or more (€16,49 here) on a game that's clearly going to collect virtual dust. You might want to hold on to it for the remainder of this summer sale.