Our apps have topped the charts (Top 2 Paid), been repeatedly featured by Apple and have over 400,000 paid downloads. My expertise is App Store marketing.
I'd tell the story of someone with a top blog that ended up getting hacked, losing their google ranking, 1000's in lost sales etc.
This should be a real case study, not made up, with a picture of the person it happened to and possibly screenshots.
This gives people something they can relate to other than just saying "You might get hacked" or "A wordpress blog gets hacked ever 2 seconds".
The good thing is, you can use SDK's to create an MVP version of the app without spending too much.
Here are three SKD's that will provide the backend service:
However, I imagine the cost will quickly scale up if you were to add 100,000's of users, but at the point you've got that kind of user base, I'm sure investors will be interested and you can build your own solution.
Using the above SDK's you could probably roll out a solution for around $2,000 - $4,000 depending on what kind of functionality you need. Note: This is very much an estimate.
Checked out your app. Stop spending on marketing before you fix these things:
1. App name - Add some keywords to the name. E.g:
GRADLIKE - Advice for college students
2. App screenshots - First two screenshots are not good. Why would you promote that it's a pain to register for the app and you have to enter email and Facebook. This is part of onboard that users hate and you are putting it front and centre! Also, I'd strongly recommend not having the splash screen as a screenshot. Again this doesn't communicate value from the app.
3. Description - worry about this last. There's no evidence tha the description has any effect on ranking in the store and very few people read it.
I think the key problem here is messaging. You are not answering the question: "Why would I want to download this app?".