Why institutions and governments invest in infrustructure instead of hiring researcher permanently? I have observed two recurring trends in Academia, both in Europe and in North America. I don't have statistics in hand but I can present quite a few examples of budgets in which the investment for new infrastructure is 1000 fold what is invested in hiring permanent research staff. For example the French government has invested 4.6 billion euros in buildings and 680 million in researcher for a large research hub outside Paris. New infrastructure, most often new buildings, are filled with temporary staff, more than half of researchers are on temporary contracts. Some European countries even have limitations on the number of times a contract can be renewed, so researchers end up moving from one lab to another, which is also an inefficient use of (public) money.

A building is only paid once, while 20-30 years of salary definitely adds up, but considering the cost of a new building we could easily hire hundreds of researcher. I would rather have more permanent staff in an old building than being in a new building with 80% of temporary researchers.

So why this agenda and why is money not invested more in people? Is it just imposed by politicians? Why don't large recent centers ask for more permanent positions to be funded?

PS: I am not even sure what tags would be appropriate for this question.
Even though collaboration over distance has become more and more easy due to technology, it is that researchers like to meet. Really, they do. And especially, they like to meet at nice places. I am pretty sure that places like Princeton would not have attracted all these great minds over a long period of time if it has been an unpleasant and crammed place.

Similarly, researchers still like to have offices.

Besides this, there is also politics: It is much simpler to allocate a fixed amount of money for one greater expense than to allocate a yearly budget. This is what I observe in my country. We see a lot of programs where a fixed amount of money is given for a specific purpose which has to be spent in a limited amount of time ("Hochschulpakt", "Exzellenzinitiative", "1000-Professoren-Programm", "Digitalisierungsoffensive") and this is often used to fund temporary positions. but it is really rare that the government actually raises the base funding of and institute to hire more permanent researchers.

Finally, the number do not really add up. You can build a decent building for, say, 10,000,000 (Dollars, Euros,…), but considering that a researcher costs (very) roughly 100,000 a year, the building only pays 100 year of research, so can have enough money to pay about 3 or 4 young guys for the rest of their careers.