I don't think it's most Americans. I think it's a lot of american (and Canadians, Brits, Francos, whatever). But that's because a lot of people are fucking stupid.
When I got my first real job, I was 19, had maxed out two credit cards already so my credit rating was shot, and had literally zero in savings. My net worth was negative.
After 2 years I had a $20,000 vehicle which I owned completely (bought for $10k at auction), was debt free, and had a decent apartment.
After 8 year I had my own house, 2 vehicles, and $30k in the bank.
After 13 years my house if fully paid off, I have a newer car which is also fully paid off, and I have $200k in the bank.
Meanwhile I have coworkers doing the same job at the same age who have $20k in credit card debts and are barely keeping up with the payments.
Being financially secure is not a fucking magic trick. It does, however, require you to have some modicum of intelligence and personal responsibility.