Money does not change everything, but it changes a lot, because every form of expression of your wealth also changes your environment.
Let's say you are a normal dude with a medium income and all your friends are also normal dudes with medium incomes. Now you suddenly have a few million dollars and you spend a little more money than usual. Your house gets a little bigger, the furnishings more luxurious, the TV bigger, whatever, maybe a convertible, the food gets higher quality, the vacations a little more expensive, the free time a little more.
All of that has an effect - on you, and on your dudes, too. Some of them will be envious, others will feel that you're out of touch, or that they're "not good enough" anymore, etc.
You yourself will no longer be able to imagine eating the cheap cheese from the supermarket, your own demands will inevitably rise.
Everything we do changes us and changes our environment.
If everything is to remain as it is, do nothing, but then you don't need several million, because you don't use them anyway.
My text sounds very negative now, but of course it can also develop in a completely different direction. You will become a much better person, your intercourse will be better, you will get new friends who are better people than your old ones and so on.