More space free

The referral system is your best bet. I made a comment about this to customer support a few months back. Some of us use dropbox casually and don't have the cash to shell out to pay monthly or yearly, specially students... 

Unfortunately, there is no other choice but to pay the time limited fees. I suggested if they could add a once a month or once every few months purchase option of x amount of space for a small fee that you can add up over the years.

Sadly, your best bet is either doing the referrals (A. You need alot of friends who already do not have dropbox installed or B. Make a bunch of fake email accounts and go uninstalling and reinstalling dropbox on a computer with each account to add space). 

Your choice. You can also be of help on these forums and hope someone gives you a kudos.  There's also the basic account setup and things you can do, but it does not add that much more space.

Hope this helped!

Don't call it fraud, because it's not. You can have the e-mail accounts on your name and do refer a friend, that is not a problem, and no they do not remove the space acquired. I've had tens of friends do this before and their accounts have been fine for years. It's only time consuming for the user doing it and the fact that there's no real paid option other than a subscription is part of the problem in itself.

Mark I appreciate your hostility, but I never said I have done it, I've known of friends that have done it and asked me to do it too. I do not have the time to be making e-mail accounts or have I needed the extra space to do so in the past 5 years.

Have a good day.

Mark is 100% correct regarding this. Dropbox has and continues to remove space from accounts where referrals are suspicious in nature. The referral system is intended for one person to refer another. Using it to gain extra space by referring yourself goes against its intended use. At a minimum you can have your space reduced. At worst, and it has happened, you can lose your entire account.

Do not attempt to game the referral system or you risk losing your account.

I think it would be good if the referral reward for free users will become 1GB instead of 500MB.

It would be as good as what I have seen on pCloud but it is still depends on Dropbox's decision.