Is it worth creating a micro rig?

Hello steemit friends,

I do have a spare computer, witch supports 3 graphic cards. I do have PSU 750W. I only need to buy 3 risers and 3 cards (probably Nvidia GTX1070) and i have possibility to buy them without VAT. My question: is it worth to go for this micro GPU mining rig? whattomine.com says, that i will generate about 3,7$ per day (after electricity bill) and it will take about 250days to get back money spend for cards.

This is yesterday calculation:
Screen Shot 2017-10-23 at 12.57.04 PM.png

This is today calculation:
Screen Shot 2017-10-23 at 13.00.22 PM.png

But what is the reality?
I'm OK. to wait ~1year to get back money spend for the cards. But what about difficulty? After 1 year it will be much higher. But probable there will be another coins to mine.

Thank you.