Yes, bitcoin is pretty extreme 
I have summarized my bitcoin investment strategy in another topic.
With stocks, I think one should take some time to find out and gather as much info as possible about underlying companies. If it is company that lacks public information on the internet, I’d avoid it… (I have been burned really badly on some Chinese stocks few years ago)
As you say there is big problem with small cap companies that they can be easily manipulated (pump and dump).
That is good news… ETFs are very conservative way of investing into whole market sector. Limiting risks (and potential gains too of course).
Interesting composition:
22ND CENTURY GROUP INC
ABCANN GLOBAL CORP
APHRIA INC
AURORA CANNABIS INC
CANNIMED THERAPEUTICS INC
CANOPY GROWTH CORP (looks interesting)
CRONOS GROUP INC
EMBLEM CORP
GW PHARMACEUTICALS -ADR
INSYS THERAPEUTICS INC
INVICTUS MD STRATEGIES CORP
LIBERTY HEALTH SCIENCES INC
MARAPHARM VENTURES INC
MARICANN GROUP INC
MEDRELEAF CORP
ORGANIGRAM HOLDINGS INC.
SCOTTS MIRACLE-A
SUPREME PHARMACEUTICALS INC
ZYNERBA PHARMACEUTICALS INC
Put aside Scotts Miracle 
Does anybody know any of these companies?