I think the benefit of compound interest can be seriously oversold

It really can't be. If a wizard invests $5,000 in the year 1900 - about the average cost of a house at the time - simply in the S&P 500 index it would be worth just over $2.5 million today, and the wizard would be our equivalent of 30 years old. This would assume they add nothing more through the years (which they probably would). And even that's only an annualized return of like 5% or so- if they had any sort of active management (according to dresden at least, they have armies of investment personnel), that amount could easily double.

Compound interest is a very real and very powerful thing.