Compare this with a 529, which serves a similar purpose. Then this just reduces to a stocks vs. bonds argument, but for your kid's education. Do you value safety or STONKs then?
Also, I find changing beneficiaries for an I bond is easier than a 529, in the event whatever beneficiary doesn't pursue college (a decision I understand more these days), but IANAIA (I am not an investment advisor?)
So this doesn’t allow you to avoid the income phase-out, it just lets you time-shift the educational spending to an earlier year (in which your income may be below the threshold).
If your family income is above the threshold in every year until you need the money for tuition, then there will not be an opportunity to get the tax benefit.
From your link, emphasis mine:
> Taxpayers can bypass the income phase-outs on savings bonds by rolling them over into a 529 college savings plan before their income increases beyond the income phase-outs.
Also, I am not exactly sure what you mean by "STONKs", but if one's investment timeline is on the order of years, all the history I see shows broad market equity index funds to be pretty safe.