How can I stop using my primary Apple ID (Gmail) but leave my secondary Apple ID (icloud) as primary ond only ONE?

Question

Good afternoon friends.
Please help me and tell how can I stop using my primary Apple ID (Gmail) but leave my secondary Apple ID (icloud) as primary ond only ONE?
I started using Apple ID in 2011 when iCloud was not exist and was forced to use non-apple e-mail adress as primary ID.
So I used GMail mailbox.
When iCloud was started I created my account but unfortunatelly can't remove this Gmail address from my Apple ID and replace it with icloud mail address.
I was VERY dissapointed because I don't want to use "outside" mailbox to get letters from Apple and ny ID.
In fact I see the Apple old users and fans discrimination.
When creating new user accounts are free to create a box on the iCloud mail and use it as a primary ID, and the only ONE.
At the same time the old user is obliged to keep third-party mail box like Gmail etc. as the primary and can not get such an opportunity, as a new user
This is extremely inconvenient and a VERY strange logical.
For example, now I want to stop using this mailbox on Gmail but I can not do that because in this case I lose access to my ID, or run the risk that someone in the future will create a box with the same name on Gmail (when name will be free and available) and will automatically get access to my accounts on Apple and to my Apple ID.
Now, to avoid this, your team, I offer the only way out: ID, create anew.
Of course it's possible, but then:
- I lose all my purchases for 3 years and will be forced to make them again and pay money for the second time for my purchases
- Lose access to the familiar iCloud e-mail address who now serves as secondary ID because this e-mail address is almost no longer available and will never be released in future.
And now answer me for ONLY TWO questions:
- WHERE IS LOGIC?
- WHAT ABOUT TO BE FRIENDLY FOR YOUR USERS AND FANS?
Thank you!
Hopefully for your GOOD answers.

Answer 1

You cannot make your @icloud.com address the login address for the ID. However you can change your ID, currently a Gmail one, to any other functioning non-Apple email address. The Gmail address would then no longer access your account, and so even if someone were to obtain posession of it (is that even possible) it wouldn't allow them to get into your account.
If you want to change your ID to another email address please follow the procedure outlined below, particularly noting the first step.
Firstly, if you have 'Find My iPhone/iPad/iMac' enabled on any of your devices, turn it off.
Create a new email address, for example  at Yahoo or Gmail, or anywhere convenient (or you can use an existing address as long as it has never been associated with an Apple ID).
Go to http://appleid.apple.com and click 'Manage your Apple ID'. Sign in with the current ID.
Where it says 'Apple ID and primary email address' and gives your current ID email address, click 'edit'.
Enter your new address and click 'Save changes'.
Now you will need to go to each of your devices and sign out in System Preferences (or Settings)>iCloud - 'Sign out' on a Mac, 'Delete this account' on an iOS device (this will not delete the account from the server).
Then sign back in with your new ID. Your iCloud data will disappear from your devices when you sign out, but reappear when you sign back in.
I re-iterate: before you start, turn off 'Find My Mac' (or whatever) or you will need the services of Support.