My first question would be have you invested in yourself up to the point there are no further marginal gains to be had?
A degree, certification, or other qualifying accreditation might be the difference in being able to save 40% of your income and being able to save 70%. To put it more concretely, if you are going to be working for the next 10 years, it will be a lot easier and faster to earn the required passive investments earning $80k than it will be earning $40k.
To be a minimum six-figure couch potato drawing $100k/y from a passive portfolio, you'll need about $2.5M. To save up $2.5M in 10 years you'll need a high-paying, high-stress career and years of preparation (e.g. doctor, airline captain, or corporate officer earning $200k/year) OTOH, if you can be happy on less, a relatively frugal lifestyle and normal career will get you there.
Beware of miracle investment products like crowdfunding, cryptocoins, flipping schemes, and MLM schemes. There are lots of desperate people looking for a free lunch and therefore an ecosystem exists for "alternative" investments. Rental properties are an investment business that can yield an ROI that starts low and hopefully increases over time, but I would not call them a passive couch potato option.