What is the free cash flow of 1 acre lot on in the ocean in Carmel? In 1975 you could buy a one acre lot on the ocean for $80,000. Now, the same lot is worth about 3 million plus. The value of any asset is set by the marketplace. An ounce of gold, an acre of prime real estate, a painting by Edvar Munch, a 1965 Mustang or a Bitcoin--all of the above have negligible cash flow and are worth what someone will pay for them. If you need to see net income, sales estimates and P/E ratios in order to put something in your portfolio then fine--put 100% of your savings in equities. That has worked pretty well over time but some see a value for diversification into other asset classes (such as gold, real estate or bitcoin) with a small percentage of their portfolio for speculation and/or as a back up in case equities crash.
The comments about bitcoin (BTC) being used by slave traders and drug dealers just shows how there is pervasive ignorance about cryptocurrency (which supports the bullish case). BTC was used for buying drugs on the Silk Road but the principal in that dark net site went to prison. BTC is not anonymous. Monero, Dash, Verge and some other crypto's are more likely to allow anonymity (especially if you stay on the Tor network).
The argument that the value of BTC could be wiped out if the US, China, Europe, Japan and Korea pass a law against using bitcoin or other crypto currencies--that actually is the most plausible of the bear case arguments. China did outlaw bitcoin and the price dropped then took off again. Government policy (in every nation) is determined by what is in the best interest of the rich and the powerful. The US may outlaw ether and bitcoin in the future but they haven't done so yet. Recently, Goldman-Sachs announced that they are looking into crypto investing. Crypto is still a minor part of the world finance picture so like a small seedling, it can be crushed into the ground. The longer it survives and grows in market size the closer we come to a tipping point at which the rich and powerful people own enough of these assets that they will not allow prevent governmental attack.