You're telling me a dude who went bankrupt 4 times flashing his cash around won't run on his own money to placate his ego? Come on! He totally will even if it's a failure.
But it's completely different. His businesses were his financial lifeblood prior to respawning as a brand due to his success at going bankrupt.
An independent campaign is going to cost him tons out of pocket to put anything on the air as his poll numbers collapse, he has to fight to get on the ballot, the media cuts him off, he never gets any shot at the debates, etc.
The reason he wanted the Reform nomination in 2000 is that they had ballot status in 20+ states, were eligible for $12.5 million in public funding AND Trump would be able to pay himself back for loans. An independent bid doesn't have that option.
Perot spent $60+ million out of the $190 million total spent on the 1992 campaign. Including $40 million in October. In 1996 Perot spent almost none of his own money, $29 million was the federal funding, and unlike 1992 he took in donations. The campaign only spent slightly more than half that because he paid himself back from it. That was out of $240 million total spent.
Historical side note, Trump ran in the 2000 Independent California Primary though he had dropped out a month before you couldn't really get your name scratched from it (John Anderson had his name put in against his will):
Johm McCain 38.03%
Al Gore 21.84%
George W. Bush 21.29%
Bill Bradley 7.67%
Ralph Nader 4.29%
Alan Keyes 2.77%
Donald Trump 0.70%
Harry Browne 0.58%
George "Boots" Weber 0.44%
Steve Forbes 0.29%
With just registered Independents he did roughly about the same:
Al Gore Jr. 234,267
John S. McCain 216,172
George W. Bush 160,308
Bill Bradley 77,646
Ralph Nader 27,833
Alan L. Keyes 20,564
Harry Browne 3,432
Donald J. Trump 3,240