Do not give up yet.
Real humans have recovered their accounts in your exact situation, but you have to use a specific strategy to bypass the "2FA is final" policy.
Microsoft’s automated recovery form (ACSR) will fail every time if 2FA is on. Stop using that form. You need an Account Takeover (ATO) Investigation, which only a human agent can start.
The "Xbox Support" Strategy (Highly Successful)
Even if you aren't a gamer, the Xbox Support Team has more powerful tools for identity verification than the general Microsoft team. They can verify you via your laptop's hardware ID or past purchase history.
Go to support.xbox.com/contact-us (Just copy paste that into the browser)
Click Contact Us.
Select Account & Profile > I can't sign in.
Type "Agent" in the chat until you get a Request a Call or Live Chat option.
State that your account was compromised, and the hacker enabled 2FA and changed the primary alias to [Hacker's Email]. You need to open an Account Takeover (ATO) Investigation ticket.
Use your proof (The Laptop)
Since you are still logged in on your laptop, you have proof that no hacker has. Before your session expires, collect these:
Console/Device ID: Go to Settings > System > About. Note your Device ID and Serial Number.
Transaction IDs: If you ever bought anything (Minecraft, Office, a $1 app), find the 10-digit order number in your email or the "Order History" tab if you can still click it.
Tell the agent that you are currently logged in on the primary device you've used for years. He can see your IP address matches the account's historical login data, whereas the 2FA was enabled from a different location.
Ask for an "Escalation," not "Recovery"
If an agent says, "We can't help because of 2FA," use this exact response:
"I understand the policy, but this is a malicious account takeover. I have the hacker's email address and proof of my original ownership. I am requesting that this be escalated to the Global Escalation Team to have the account locked and the 2FA reset based on my billing and hardware verification."
Create a Safe Landing Spot
Microsoft cannot fix your old email if the hacker changed the alias. Instead, they usually transfer your data and purchases to a brand new Microsoft account.
Create a fresh Outlook/Hotmail email address right now.
Do not link it to any Xbox gamertag or services yet.
Keep this email ready to give to the agent as the target for your recovered data.
Please don't give up. If you walk away, the hacker has your personal files, contacts, and possibly your payment methods forever. Even if Microsoft can't give the account back, you should persist until they suspend/delete it so the hacker loses access too.