As with anything in life, ignorance is the greatest generator of fear. 80% of Americans have no business with a credit card under any circumstances. Out of the other 20% that do, well over half are so risk averse that something non threatening paralyzes them at least once a day, and financial institutions are at the top of that "fear factor."

Out of the top of the 20% who are responsible, a few bucks a year and free flights isn't worth their time. We are talking about a small niche of people who are responsible AND the hobby is worthwhile. Sign up bonuses for business travelers is a good way to get started.