Why will paying lower fees result in a less secure network? It is not the fees that make the network more or less secure. The difference between being more or less safe is the number of different miners - the more there are, the safer.
The hashrate didn't grow from 1 petahash to 400 exahash becuase there was a $1000 pot to be earned a day.
Again, end scenario is that fees will be the only reward miners will get, you think you will have miners with the same hashing power on 600k a day tx playing each 20 cents?
I already gave an example of accounts:
a) 10x50$ = 500$/block
b) 2000x0.50$ = 1000$/block
Which is more advantageous for the network? I believe the second option is the best. It pleases both miners and users.
Yeah, the only problem is that you've stopped short of the actual capacity, so let's get the picture of the real situation:
- block reward, 6.25x144, 900 BTC, ~ $ 31 million
- current fees in the last 24 hours, 106 BTC ~ 3,5 mill
- transactions in the last 24 hours, 516,878
So for the fees to cover the block reward you have two choice
- people pay 10 as much
- you have 5 million tx in a day...
But as you can see in a multitude of other topics, 10 MB blocks would break the law of the universe!

Not to mention it will also break and turn into dust the ego of some!