It's not a static situation where you would go from 150% to 10% roi everytime, in many cases I've changed my bid $0.001 and the roi is 3% less. And yeah I'll take 80% of the traffic and 10% roi or negative roi for a few days to try and get rid of someone who doesn't know what the fuck they're doing. Sometimes it works, sometimes you are going against an autobidder, and then sometimes thousands of the refined longtail targets you dug up are suddenly being outbid all at once(the platform itself). It's not outside the realm of futility.
There may be other bidders in between you as well, so it's not like every time you can just opt to get 50% of the traffic on the 2nd bid and the same roi, you may go down to 10% of the volume or less with little margin.
On trafficvance you are still staggered if you bid the same as other people. The first person to bid that amt gets #1 and the bulk of the traffic, 2nd person to bid the same amt is 2nd, and so on. You wouldn't all get the same volume.
One of the ways to get volume without worrying much about bidding is to monetize the top volume urls which is what I've been trying to work on lately. It's harder but it also weeds out the majority of people who aren't creative enough to monetize them.