Investing might be tough, because banks report cash deposits of $10,000 or more to the government. At some point, someone, somewhere , will start asking questions about where that cash came from.
A single deposit *might* pass as not being noteworthy. Multiple deposits would set off alarms.
I always wondered what I would do if I found and kept a large amount of money. Just make small to modest cash purchases for the rest of my life?
Lots of real estate is bought with cash. That could use up a lot of it. But do it gradually.
You could also, over time spread it out in various stock & bond funds. Again, over time, smaller deposits.
Pay off all your debts first.
One thing you don’t do is display it on your bathtub, start taking selfies & yacking to ANYBODY about it.
If you have 7.5 million you do not have to worry about investing it anywhere.