Coinbase wallet potential scam or maybe not?

Hello , My uncle is old (80) and he met a girl through Facebook, and he sent her $4,000 to invest in crypto for him.

After months, he asked how things were going with that, and she said everything went well and your balance is $10,000.

She asked him to create a Coinbase wallet account, and she transferred ETHERIUM META $7.904 (which is on display on his app), so I live in California and he is in Oregon. I tried to help him cash out, but everything we tried was saying: YOU DONT HAVE ENOUGH USDC.

Also, he received an email from [[email protected]](mailto:[email protected]), which I think is fake, asking him to transfer $3,000 to them so the account gets unlocked so he can cash out.

I thought 100% was a scam, but also, I'm not the smartest person; I pave roads for living.

Is that just a display of money, so people are sending them the money asked for in the email? He is really old, and it makes me sad that people are trying to get him like that.