Real estate investment makes it possible to build up lasting wealth (which can allow you to quietly prepare for retirement, protect your family from any vagaries of life, etc.), unless an incident occurs (i.e. degradation of the property), it is rare that real estate loses value and depreciates. The property does not suffer the variations and fluctuations of the stock market. Even under the health crisis (i.e. Covid-19 pandemic), real estate prices have not fallen. Reselling later can also allow you to benefit from the real estate capital gain. 

Overall, Paris is a safe bet in terms of rental investment or pied-à-terre. Variations in the price of real estate remain stable, with prices slightly increasing from year to year. The major economic crises of the last 30 years have not allowed the market to fall in the long run.

Nevertheless, apartments with defects in Paris have trouble selling or do not sell at all in times of crisis. Exceptional, rare, and flawless residences with high ceilings, a balcony/terrace with a view, or even gardens sell well and often at above-market prices. Properties that do not require work are more sought after and sell better than those that require renovations. As such, it's vital to evaluate the opportunity of a real estate purchase by quantifying the cost of the work without forgetting to take into account the cost of notary fees in the purchase of an apartment in Paris.