- No way of limiting the expenses AFAIK. I don't want the possibility of having a huge bill on my name that I cannot pay. This unfortunately applies to other clouds.
- The risk of being locked out. For many, many reasons (including the above), you can get locked out of the whole ecosystem. I depend on Google for both Gmail and Android, so being locked out would be a disaster. To use Google Cloud, I'd basically need to migrate out of Google in other places, which is a huge initial cost.
Both of those are basically risks. I'd much rather overpay $20-50/month than having a small risk of having to pay $100k or being locked out of Gmail/my phone. I cannot have a $100k bill to pay, it'd destroy everything I have.
Also I haven't needed it so far. I've had a Node.js project on the front page of HN, with 100k+ visits, and the Heroku hobby server used 30% of the CPU with peaks at 50%. Trying to do the software decently does pay off.