Antminer S15 example:

1612.70 EUR setup
4.85 USD daily return (whattomine estimate)
ignoring USD/EUR exchange rate

1612.70EUR / 4.85 USD/day  = 332.5154 days

Now add the monthly fee of 72EUR and look at year...

(1612.7EUR + (12 month * 72.0 EUR/month ) ) / 4.85 USD/day = 510.659793814433 days

So currently we are looking at a break even in about 2 years by current BTC prices and the difficulty is not getting smaller...