So your theory is they know how to make a vaccine that will last for life, but they didn't because it would make them less money?

a) This would require global collusion and conspiracy, since any vaccine maker who could make a durable vaccine would drive its competitors out of the market.

b) This greatly overestimates, IMO, the capabilities of our biotech/pharma industry. It's an amazing and spectacular achievement that they were able to make working vaccines at all in a < 1 year time frame. They don't have any secret immunity-boosting technology in ther back pockets.