Dedicated servers == constanct cost.
Many cases, you reach peak times for several hours per week/day. With GCP scale up and super fast, and when done, tearing down and saving money.
Also, from my experience, when you reach a certain level of operations, you discuss with Google sales team and you get a significant discount for bandwidth.
We're well past that point (with AWS) and we get a meaningful discount, but it's in no way competitive on a per-TB or per-Gbps basis with a dedicated colo.
It's also higher quality of service IMO. When AWS gets their daily DDoS traffic, they manage it and we never notice nor care. With smaller colo providers, they are much cheaper, but if your neighbor is getting DDoS'd, you notice it. I assume Azure and GCP are similar.
With regards to DDoS: that's something where OVH has surprised me well in the past, I've been a target once or twice, but they automatically handled all the upstream issues, and thanks to their hardware firewalls, I could filter the traffic before it hit my server.
On Twitter, the OVH CEO claimed that they've previously had servers targeted with 1.1Tbps DDoS, and still managed to keep that user's site working.
Also, from my experience, when you reach a certain level of operations, you discuss with Google sales team and you get a significant discount for bandwidth.