Well, to be honest, Vultr has 2.5$ (IPv6 only) and 3.5$ plans. So, if they're getting by, so could DO.
https://www.vultr.com/products/cloud-compute/#pricing
I actually migrated from DO to Vultr because at the time DO offered 512 MB RAM for $5, while Vultr offered it for $2.5. And Vultr gave me $50 bonus platform credit on sign up, valid for about 18 months (accounting for possible overage fees).
I'm still on Vultr, 3 years on. No problems at all, other than billing issues (accidentally was assigned Australian VAT despite living in Serbia), I had no support tickets. After some time I started using more instances, and more powerful instances, and more services (block storage, "portable" IPs, object storage, internal networks, etc).
I've had a lot of problems with DO's Object storage which was also one reason to move away from them. Problems were quite catastrophic in nature, i.e. the files were unavailable for a few hours every few weeks.