It will keep getting worse,-quickly if you keep walking on the spot.

Why does this happen??? I think its a combination of age and moisture. Moisture over time seems to weaken the foam. I've heard some claim its the constant stepping on the hull that mechanically weakens the hull.-But I think that perceiption comes from that is the most locally stressed place where already weakened foam gives way.

A hull that has delaminated once is more likely to have future problems. But its worth fixing, if you already own the boat. But I wouldn't spend a lot of money on buying a boat with soft spots or delamination repairs.-Absolutely, never spend over $500, and try for $300 or less, depending on the parts value of the boat.

The lesson here, is to make the effort to drain and keep water out of your hulls after sailing.