There's some of that, but even rolling your own on oss software, your infra (compute, storage, network) can start to balloon really rapidly.

TBF, I think this is more of scale problem for medium to larger traffic companies than startups. I've seen this become especially acute when you're transition from a small or medium company and have started to hit those growth curves, and you get socked with these surprise bills. Something that was a tiny line item suddenly becomes... bad.

It truly is interesting how much this happens. I felt pressure to use an investor's staffing company at previous jobs.