Were you to start flying tomorrow, you could be done with your training in a year and instructing, and at a busy place, be nearly to the experience necessary for the ATP in 1-2 years, and then off to a regional airline.

Among that looked at by an airline is your credit history; it speaks to several areas of interest to the employer. One is your ability to live within your means, and another is your commitment to stand by obligations. It's not a perfect metric: people get sideways thanks to many things. Divorce, medical setbacks, economic ebbs and flows, school, etc.

Regional pay is a kings's ransom today compared to not so long ago. It's never been better. Never the less, it's hard to pay back hefty loans and live the commuting life and save or survive on that; thus credit has another level of impact: can you live within your means, knowing what you'll make and what you'll owe?

The hardest part of learning to fly is paying for it. Were it a simple thing, everyone might do it, but what drives those to enter and stay entered in the business is motivation to fly that exceeds all liability: without that, the chance of success is low.

If airlines are the goal, entering at 45 may not be a path to the majors. There are many avenues in aviation and many destinations that do not lie at the airlines door; there are a lot of avenues. Not all wear a uniform, and many are quite rewarding in their various ways. Whether the reward is worth the cost is entirely up to you.