People’s criticism isn’t just about the fact that some of his ventures failed (which you're right is common in entrepreneurship), it's the patterns, ethics, and consequences tied to those failures, especially when he’s held up as a business genius deserving of leading a nation.
He’s been involved in over 500 companies, and while some succeeded others failed spectacularly. His casino bankruptcies are well publicized. Trump has a pattern of overleveraging, where he borrowed heavily, often on shaky foundations, and left others holding the bag when things went south. Banks, bondholders, and contractors lost out, while Trump often walked away relatively unscathed, thanks to legal protections and restructurings. His “reckless/gambling side” isn’t a quirky strength but a liability that screws over employees, investors, and small businesses like the contractors he has repeatedly stiffed on payments.
I'd also say there's a difference between being ultra-cutthroat in business and just preying on vulnerable folks like students, donors, workers while hyping his own brilliance. The Trump University scandal and the Trump Foundation scandal are examples of defrauding people of millions of dollars.
He inherited a huge amount of wealth and he's likely lost value by being an active entrepreneur rather than just a passive investor. At the end of the day he's just a dude who likes to gamble with other people's money, and he's never accountable when things blow up. The “obsession” isn’t about failure being unusual, it’s about a guy who touts himself as a genius while leaving a trail of wreckage, ethical scandals, ruined lives and exaggerated success stories.