He has come to realize he is not the right person in the right place at the right time - maybe 8 years ago - but not now. He can't just bow out of the election and upset the apple cart so he's staying in and running against himself.
As a patriot who wants what's best for our country - he's sabotaging any chance he may have had to be elected with flips, flops, flaps, missteps, backtracks, silly lies and by accepting a running mate who will help guarantee his loss.
The alternative is to imagine that anyone could be so out of touch as to think that what he's been saying, combined with his at times bizarre behaviour, would appeal to a majority of the American people.
I'll give him the benefit of the doubt - that cagey old politician has everybody fooled.