Is Pinsir worth powering up?

Not overly. Bug doesnt have much of an effectiveness profile that other pokemon dont cover better. In the rain it was a good counter to mewtwo and other psychic as well as dark type, but without weather, bug isnt as good as some other pokemon that are more widely useful. If youre somewhere it rains often, it will be useful against the lake trio and Cresselia, but otherwise not overly useful.

It and Scizor are the two best bug types, soon to be joined by Yanmega. The problem is that bug type is pretty niche in its use - without weather boost they lag pretty far behind other counters. Pinsir in particular had a niche against psychics that knew fighting-type attacks such as Focus Blast Mewtwo. Bug's utility against grass isn't prominent right now save the oddball gym defender, and even then a good chunk are poison sub-typing further reducing their effectiveness.

It's a neat perfect but if you have better counters against dark and psychic types it's not worth it.

Its not worth powering up right now. If you had 1 million + stardust, then whatever go ahead and do it. But with 70k... Just save that Pinsir till it gets his Mega evolution or a better raid boss with weather.