a profit model like a snowball effect - return the investment on leads and growing your list

Is that "snowball" effect and return my investment on the solo ads or any traffic source - with list building is really working well for you guys and it's so simple?
i mean, If i'm promoting affiliate products, that concept:
I'll pay 60$ for 200 solo ads to my squeeze page> 60 Opt-in to free gift> i a self liquidating offer gets me3 sales from affiliate offer >some more follow up emails and sequence with other affiliate offers > earning total, let's say, 120$ ROI for that 60$ i paid....
and then i take this 120$ and do it all over again and again... 120 options...6sales...240$...and so on. Of course my affiliates offers has a funnel and upsets and i might get more and more money with the time...but i'm talking about the system- it's really what's works?

So, is that really that simple? Of course it's not accurate and it's really depends on the solo ads vendor and..well..the core offer and the funnel and conversion rates - but generally - is that the real concept that works out for the successful marketers?

Please give me some tips and advices on how to improve this model..
Thank you!