I gave my largest single campaign contribution ever to Rand just 2 days ago.Would you have been happier if he had stayed in long enough to collect even more of your money even when he knows there is no path to victory?
The debates were his only real chance at changing the conversation and getting his message out. Once he was out of the debates then he would get no more of a podium than Santorum or Huckabee on the campaign trail. Yes he is focusing now on his Senate seat but that isn't the reason he suspended his campaign. He suspended his campaign because there was no longer any benefit of staying in.
It was clear to me for months that spending money to fight Trump in the fall was pointless - it wouldn't work and whatever benefit might come would be temporary. Rand quits now, disappointing, because whatever reason to spend money is right now. It's just the least pointless time to spend money. 5th wasn't 10th. But, meh, whatever.