Don't buy unless you have an immediate redemption that will drain your Rapid Rewards account below its current balance.
Nobody should be saving up frequent flyer currency for funerals or aspirational trips or God forbid do manufactured spending for airline miles. There is a good chance there will be a major devaluation at all airlines before the funeral or aspirational trip. The ideal balance in your frequent flyer account is zero.
Sorry.... but a balance of ZERO is not what works best for many people. If you have zero points, then you should not be bothering at all. We have a fair amount of miles and have not paid for a flight in years and we fly often (or did before March). If had zero points, we would have to PAY.
I do agree - saving for a possible flight in a few years could be wasteful planning. Or having upwards of a million miles either.
But - why zero?