Steam app won't launch

Hey Folks!

I'm having an annoying problem. I used to use the Steam app by Valve for a bit of gaming on my iMac a couple years ago. I wanted to pick up with it and do a bit of gaming but the app wouldn't launch. So, I deleted the app and reinstalled.. it installed fine but crashes on launch, in fact it seems that it just fails to launch.. I get the bouncy icon in the stat bar for a brief second and then it's gone altogether! What the?? I've tried to reach out to Steam support but get zero response. So annoying.. does anyone have any advice or can provide an assist???