Does a skyrocketing penny stock imply a successful company?

A penny stock that skyrockets and holds value is no longer a penny stock. Bitcoin is 8 years old and has hit $1000 USD twice now over multiple years.

The "market cap" is currently over 16 billion dollars. It would place 68th when compared with 192 countries M1 money supply (2015) data: https://www.cia.gov/library/publications/the-world-factbook/...

The hash rate securing the network is currently at 2.5 quintillion operations per second which is really 5 quintillion SHA256 operations every second: http://bitcoin.sipa.be/ Speaking of pennies... if every operation was a penny laid flat on earth, you could cover the surface of the earth, land and sea, twice over every second.

Bitcoin surpassed the penny stock phase a long time ago.

If it stays 'skyrocketed', yes.

Is this a currency or just a (totally speculative) stock then?

It's Forex which is both.

How would you decide that?