Anthropic (iirc) said that GPUs have a failure rate of 10% per year, so you will have to replace them with an upper bound of something like 10 years.

Also, power draw is a huge cost factor, and newer models are more power efficient. If you want to stay competitive, you will have to upgrade.

Same for density. Data centers take time to build and face ever increasing opposition. By increasing density, you can improve competitiveness as well.