Easy for someone with his own campaign plane (which he charges the campaign for) and has enough money to run without outside help.
Let Donald give up using any more of his money than the amount any other candidate raises in hard currency. So say Ted Cruz raises $12 million in a quarter then The Donald can only use $12 million of his money (including what he charges to use the plane). Don’t think he’d go for that.
Er, Trump has only used $1.5 of his money. Even including contributions, he has run a campaign that leads in all national polls on a tiny fraction of what the others have spent.
Why not? Trump is spending a lot less than the other candidates.