Nice to see your income rise so much just before you die and a lawyer gives it all away. Alas “the old have the means but no mobility, and the young have the mobility but no means”
What are you even talking about? When you retire you stop accumulating savings and start spending it. At first it continues to grow but if you plan correctly you will have made good use of it by end of life. Then it will be depleted.
By the time you retire you have more capital accruing interest, and generally more to invest in the attendant better investment opportunities available. That's what they meant.
My guess would be that there are very few people out there, at any stage in their career besides retirement, for whom interest and capital gains are more than a tiny fraction of their income. For most workers, things like salary, bonus, and (for a lucky few) stock grants make up 90% or even 99% of our income until we retire.