transactions fees depend on number of people who are sending coins at the same time. If there is high volatility in the market - the transaction fee goes up
It depends on the network delay only not depends on the number people ttansct itm you may find the many people own ths mining farm and doing that work as a main job.
In the time hard fork you will find the bitcoin transaction seems slower and you will get the transaction fees also higher due to block increasing with the segwit2x activation.