We got to be mature. Microsoft (and many other corporations) are a problem due to their unfair practices. But this is not a moral war against them, when we are not the problem. If we have vscodium, which is opensource and it has telemetry removed, which is the problem?
I would be happy if they didn't made the internet a worse place, if they weren't greedy billionaire assholes, if they didn't have a monopoly, but vscode does not affect my sleep.
You put your ability to work efficiently into the hands of Microsoft. If they stop development or go into a direction like google did with ad-handling in their browser, or unity with their payment-methods, or does whatever a greedy company does, your tool is broken.
The time and effort you put into a piece of software is valuable. And deciding to put it into a Microsoft-product instead of a true free piece of software weakens the competition. Monopolies in the making shouldn't be supported.
All the add-ons that are made for this Microsoft-product are wasted time, as soon as Microsoft fucks up - and they will. This time could have been spent in better ways.
And my last point why using VScode/ium is a problem is that it is advertisement for Microsoft. It could be a gateway to look into other Microsoft products for young developers. If you recommend them a FOSS tool instead, you might win some for the idea of a more FOSS world.
This 'somebody' has to be a great team of software developers to keep VSCodium alive, if Microsoft abandons the project. I wouldn't bet on it. Would you financially support those developers?