Tall cactus with the wobbles

[CrazyPlantLady]

My mother has an about 3' tall Pilosocerus azureus that is looking a little top-heavy. The base is a lot narrower in diameter than the top, with about 2" corked. She's had the cactus for over 25 years and we're getting concerned about stability. Would it hurt the cactus to sink it deeper in the soil when repotting? Are there other options to make sure this top-heavy treasure keeps on growing?

[greenknight]

Don't plant it deeper. It won't grow roots upward into that extra layer of soil, so that will stay wet and likely cause rot.

It's normal for the base to be narrower than the top, that's the way they grow. Usually not a problem, the stems are very strong.