If you, personally, were reasonably good about general computer hygiene, your odds of success in upgrading would go up considerably. The average computer user,

If you, personally, were reasonably good about general computer hygiene, your odds of success in upgrading would go up considerably. The average computer user, however (sample size of the hundreds of people I interacted with during the years when I did IT consulting for individuals and small businesses) did not have the faintest idea what they were doing, and it was likely that an upgrade would fail for one reason or another. I think my failure rate got to about 30% before I stopped even trying to run the upgrade and just did a fresh install after backing everything up.