Your logic is pretty faulty. It isn’t about a VP costing a ticket the election. That’s not how elections work. It’s about that VP candidate not having enough supporters of their own help their ticket win.
Lloyd Bensten didn’t have enough supporters to help Michael Dukakis overcome George H.W. Bush’s supporters. Not even in Texas. Already knowing that Bensten supporters were outnumbered by Bush supporters, it would have been insane for the Democrats to nominate him in 1992, as his loss would have been a forgone conclusion, just as it was a forgone conclusion that Walter Mondale was going to lose 8 years earlier.
Mondale only got the nomination in 1984 because the Democrats didn’t want to sacrifice Gary Hart to the coming Reagan landslide. That’s why they threw a spent candidate at Reagan. Little did they know Hart would implode on the Monkey Business 4 years later.