I've reached Platinum status by spending on my Delta Amex Skymiles Reserve.
Spending 120k has given me the 75k MQM's I need and 25k for the MQD Waiver.

I can get a Diamond MQD waiver by reaching the 250k threshold, but unless I'm missing something, there is no way to reach diamond without flying to get the necessary MQM's.
If that's the case, I want to stop trying and put the charges on my regular Amex.

My question is, are there other ways to Earn 50k MQM's other than flying once I exhausted the 4 MQM's bonuses on the card?
Can I get to Diamond without extensive flying?

Thanks for your help!