Despite some very famous recent losses, France historically tended to go to war with and win against just about everyone on the continent, as such everyone got a bit salty about it. These days its just more of a meme.

Never understood the hate for the French.

Just look up their colonial past. Before you think "That's old stuff now", some places still suffer from French colonialism today

One of the founding principles of the (CFA, African Financial Community) was that colonies had to keep 50 percent of their foreign currency reserves in the French Treasury, plus an additional 20 percent for financial liabilities. Thus, member states only retained 30 percent of reserves within their borders.

The monetary zone limits industrialization and economic development and discourages trade among member states

It's because insults in French are much better. Insulting in French is more cathartic.

I thought everybody knew that since 2003

Tbf, english insults are generally very lame compared to French, Italian etc etc