Meaning, this is too often how I see competitive bids going over time:
1) You sell a widget for $100, and it costs you $50, so you spend $10 on the ad, & make $40 margin.
2) Your competition gets in, & has similar price/costs, & bids $11 on the ad.
3) After a few iterations, you both bid $49.50 for the ad, making near zero (positive) margins & stay in business.
4) But, VC-backed businesses enter that market. The VC (rightly) tells the startup that they aren't going to make profit in the first year anyway, but they MUST show user-growth. And, here's the VC money to pay for user growth.
5) So, the VC-backed startup bids the ads up to $100+, far above profitability for legit bootstrapped or existing profitable companies.
That's how the ad budgets can be drained in the ecosystem.
I know a lot of investors here that don't want to take the blame for this impact and may downvote me, but I do see this happening for many keywords over time. I don't need to be popular on this issue.