I used to run my own ad co, which I sold to another ad co. Prior to that, I worked at one of the largest ad cos (@google)
Here's a Sat crash course in ads based on being in the trenches:
Performance marketing budgets will always stick around as long as a marketing channel is making a co $$ profitably.
That's about all I have to say on ads themselves for now. But a LOT more learnings on ads + conversion methods for another day...