depends where the stress is
'take off' or 'market'
there's certainly a 'market' (non-profitable) one. just take a look at reddit politics, nationstates forums, supremacy 1914 chat all filled with active posting youth of 50 000, 10 000 and 500 users in descending order. the problem is this forum has a shit layout, it's also old, has its prejudices, has edgy people, has (or at least used to have) a reputation for nazimods and zero organisation or initiative.
'take off' as above, but depends on expectations. YD just needs something to do alongside it to make it worthwhile to press while opening chrome homepage. a more developed RP with some low-level graphical representation alone would do the trick to double this place. it also needs some ownership.
something like this isn't the place for an 'investment' or 'charity'. the only way something youth-politics related could be an investment is if it's your hobby, you're prepared to spend a few hours on it a week and it gives you profit, like allegrif. principle of incentive still works.