Is being a motivational speaker a wise career choice?

This will ultimately be a personal decision, but in the broad scheme of things, probably not. Motivational speakers are paid per appearance, so it can be very difficult to set yourself up as a motivational speaker without having either a traumatic life experience or a set of credentials that will convince people you are a good speaker. Also, you only get paid while you work, so if you have a cold or bad weather prevents you from getting to an appearance, you don't get paid. You would also be classified as a self-employed person, so out of your speaking fees you must pay income taxes, Social Security taxes and any other federal or state taxes on income that employers typically withhold from their employees' pay checks.