> If I spend a bunch of money/time on new guys I have less to spend on experienced guys compared to the company that just spends it on experienced guys.

That is the theory - in practice it is a bit different.

It takes a lot longer to become a senior who can easily switch business domains and tech stacks than it does to skill up in a single business domain and tech stack combo.

Two years in house is easily comparable with 5-6 years on the market if you work in a complex domain and have a good training program.