Let's say 500€ daily rate (which is probably average in France with a very large standard deviation between Paris and deserted zones and factoring varying daily rates which are domain specific and experience related. No way a junior RoR freelance would make 500€ in Massif Central for instance. Likewise, 500 is low for an experienced data science freelance working in banking in Paris). 206500=60k€ gross

After social contributions, 30k€ net revenue in France (actually a little more but I take the liberty to round that down).

In large cities, 33% of revenue for housing is not uncommon. We're left with 20k€, of which we have to substract revenue taxes (rule of thumb in that revenue range, about 1 month revenue per year) so here 5k€. 15k€ for 6 months. living frugally you can probably save 2/3 so you can save 10k€ in 6 months.

Assuming these ratio, it would take 2.5 years of steady, near fulltime employment as a contractor to save these 50k and go all out on your project.