Those who brag the most...
This. The flashiest people are usually actually the least financially sound, and are often crooks to boot. Most people who don't know better will assume someone is doing great when they see all of the flashy, expensive stuff, and will often buy into whatever they're selling or "invest" in their scams or whatever.
Ask to see their audited financial statements, tax returns, the deeds to their homes, the titles to their cars, their SEP IRA's, brokerage and bank accounts, etc next time they ask you to "invest" or tell you how "rich" they are.