Yes some power up very fast, HR is very important, coins are the most important in the beginning..
I understand It was a very short time from when I started and many had swords at lv 100 plus... Doing the math it doe's not add up with the price of each upgrade where do they get the coins... I am vip 5 and Highest sword is 80 rest is 60 but they had 100 long ago... If you use rune power the higher swords even though they show less power will beat you.. Don't give up Many power up 1 hero to make 1 with huge power you may not be able to beat them today or even in a month but even is better... In time if you keep powering up it changes... Some heroes lose power and their is a point where they stall out like queen p...

Start off using your coins for runes and only attack runes once you are able to get them.. Don't reset very many cool downs with gems just power up runes... this gives you time to build techs and blacksmith discount saving you a bundle.. Save some gems get runes with those coins. Also saving for a mount slowly knowing you will need 1 later in the game but keep slowly powering up while saving so they cant see it and revenge you ouch...

I am #4 on the server so far but have not coined past vip 5 many others have coined a lot more so I wont be 4 for very long without adding to that...
I am currently beating everyone in HR my only problem is stamina.. If your having a hard time beating HR bosses look thru forums type the name of the boss many can be beat with the right heroes with 0 saints and 0 stars you just need to know the form then ht them over and over again until they go down..