Where I live none of the storage companies will let you pre-pay 1 year of rent let alone 5.

A major part of their business model is giving low initial rates and then raising the rent over and over knowing what a pain it will be for the renters to move to a different storage place.

The industry acronym for the strategy is "ECRIs", existing customer rate increases, and it is a profitability metric they track.

To be clear, it is in storage for the past 2+ decade. It was moving houses every year, the last few years, with only the essentials, that made me realise how much of a hoarder I was. Nevertheless, dumping it somewhere and "forgetting" about it is not much of a solution - as someone else said here, you are just passing on the problem to the next generation.