Belgium has in normal cases 0% capital gains tax (only EU country I think), a strong passport for travel, strong welfare. I would say you benefit very little unless you fear or plan to do something that angers the government or its overlord the EU, or if the Germs invade, indeed lol.
Maybe for some E-businesses or god knows what happens with Russia.
Other EU countries have much higher taxes, more invasive laws that makes it easier for people or businesses to get closer to your assets, worse welfare, etc.
Belgium is suckling the EU tit quite well. 1/50 people in Brussels is a lobbyist. Thats a lot of money flowing in.
So if you can tolerate the EU very little, but if you cant then probably like Fleece said a lot.