zoe True, but the financial damage of buying a new Pixel is higher than the damage those threat actors could do to me.
Only you can put a figure on exploitation cost. But it may not be necessary to compare against the price of a new Pixel. Pixel 6a's still have two years of support left, and 7a's have three (source).
A used device might end up needing a battery replacement, which might be expensive, but an old 4a might need one soon too. And a 4a is arguably more likely to run into some fatal failure (RAM, flash).
New devices are indeed expensive, but they are not the sole alternative to EOL devices.