The thing about the wall is that even if it costs half what Trump said it would cost, and he thinks up some way to pretend that Mexico is paying for the wall, America still has to find billions of dollars to build the wall.
Meanwhile there is no evidence at all to show that Trump is a good business man. He has several failed businesses, and nobody knows anything about his finances.
If you could clearly judge people's financial wealth by their bling we wouldn't have had Maxwell, Enron, Barings, 2008 crash etc. etc.