You have gathered 800k from a hosting, let's imagine that there are more than 800k together with the other services. Which indicates 1600k images listed from the forum. Let's round it up to 2000k images.
I count about 2.5 million image links in my data collection. Some of those are dead already, so your estimate is close enough.Quote
But even a VPS has file limits. The service you use goes up to 58,000,000!? 
The "58 million" is the number of inodes on a 1 TB disk. Most files aren't that small, so the number of images you can fit in 1 TB will be significantly lower. So in most cases, the number of files shouldn't be a problem before you run out of diskspace.AWS S3 is really the most cost-effective option.
I did a quick price check:Quote
First 50 TB / Month: $0.023 per GB
AWS is very reliable, but quite expensive on bandwidth. 10 TB doesn't sound unrealistic, and would cost $230 per month. Contabo (I think TryNinja still uses this) gets you 32 TB bandwidth for €17.49 per month. And unlike AWS, that includes the rest of the server too. But it probably won't reach the same very high uptime AWS has.