Was it a bubble? We'll see. It sure looks like it. But, hey, maybe it'll be different this time!
With a stock the money from investors is needed to operate the company offering the stock. When the value reaches a critical low and the company becomes insolvent, it all goes to hell. Bitcoin is different. It does not need the money to operate and the price can fall or rise without destroying it's utility. No matter how low it goes, it could go up again. Not true of stocks, bonds, derivatives and most other financial instruments. The closest asset in terms of behavior may be gold. Gold has seen countless bubbles in the last 4000 years, and is still able to set new highs.
Most stocks are shares in a company that already have operational founds, and it's really about the valuation of the firm as it is. A high stock-price will help a firm to get good lending deals etc. but they don't use the stock market as a "cash pool".