Money is in the eye of the beholder. Or something like that...
Personally, I don't have that many pictures that I want to save. I do take several every few weeks, but usually to share with some one about something I'm working on. Once I've shared them, I delete them; they've served their purpose. I did pay for SWMBO's 50 GB, it's more important that she always avoids any 'warnings' if I can help it!
You've probably done the math and discovered that 50 is ~10 times as much as 5... The number of images that can fit into that space greatly depends on the sizes of their file. Just remember, newer cameras almost always have higher file sizes because of their ever increasing resolution. Just like computer memory, you'll never have enough disk space, whether it's on your desk or in somebody else's building/'cloud'.
Little known secret: Cameras in our phones and 'cloud' storage were invented to 'encourage' us to take way more pictures than we need and then be too lazy to do anything with them, especially culling! "But they are
MY pictures! They are unique!" Of course, worthy of keeping is a completely different subject.
The real purpose of the technology is to sell new products and space to keep stuff we didn't know we needed. The same thing is visible in the proliferation of self-storage places... Retails golden rule: Buy stuff now (even if you have to borrow to do it) and then pay some one to store it for you!