I'll share my personal experience.

I have an apartment rented for over 10 years, which I'm renting at way below "market price", whatever that may mean. In the area, the rent for a single bedroom apartment is in the €1200/€1600 range; I'm renting a three bedroom for roughly ¼ of that and I do not intend to hike it. I kept the rent frozen for nearly 10 years, during a period when my country was in the shit after the 2008 market crash. I started raising the rent some five years ago, roughly 2% every year, by the national rent actualization index published by the government, which is calculated taking into consideration the year's inflation rate. Fuck scalpers.

Parallel to that, I managed to put and still put some every month towards an investment fund and a special saivings product my country has, where a percentage of what you put aside is deductibke towards your income return; these products, upon maturity, are more fiscally advantageous than investing in stocks or ETFs. Regardless, I also keep an ETF on a broker but haven't had the capital to reinforce for some time now.