Various studies have shown that giving a gift of $X to someone brings more happiness than receiving $X. Of course, people who are economically marginal need the money more than they need the positive feelings of helping someone else, but that isn't your current situation. Take your time and investigate some charities. Don't make one big donation; by spreading out the time considering things, you are also spending more time imagining how many people this could help.
One important concept is: effective altruism: https://en.wikipedia.org/wiki/Effective_altruism
One shouldn't pick a charity simply because they have the smallest overhead. Pick one which can do the most good for the worst off. For instance, yes, you could buy a custom vehicle for 50K euro so someone without legs can drive around, and it is fantastic for that one person. Or with that same amount of money you could literally prevent ten deaths, or 1000 cases of blindness through medical interventions in some of the poorest countries.
Here is an example: if a woman is in labor too long, the pressure of the fetus can cause an ulceration of the woman's vaginal wall. Without proper medical care, it leaves her with a permanent hole between her intestines and her vagina. As a result, gas and feces can freely run out of her vagina, making her a social outcast. $750 is what it costs to give such a woman the surgery to fix this and a month to heal, allowing her to return to a normal life.
https://fistulafoundation.org/
You don't need to give everything away. Start with an amount that is significant but doesn't materially effect your lifestyle, say 250K euro. Then find a basket of charities that are meaningful to you over the next year, and donate. After that year, decide if you you want to do more or not. If not, at least you helped some people and you still have 95% of your windfall.
Finally, as other people have said, don't advertise your wealth. You will find "friends" who are happy to spend it for you. At the time it will seem fun and exciting to have so many friends doing so many things with, since it will be filling an emotional hole which you've expressed. Unfortunately, this exact scenario happened with my son (a smaller amount than yours, but over $1M). He had a lot of shallow friends for a couple years until the money ran out.