I get asked this question a lot. I am going to try to answer it differently here.
Bitcoin with it’s Block chain technology allows a network of computers to track ownership of Bitcoin for people all over the world. Before, when you logged into your bank or a game, that companies servers told you how many credits that you owned. Now, a collection of computers owned by many diverse individuals around the world confirm how many Bitcoin you control. Another network of computers facilitate exchange of these coins between parties and report transaction data as price.
This price data and amount of Bitcoin allow us to perform transactions with each other for goods and services in this alternate economy. You could treat this market data as an ebb and flow for Bitcoin. When the price is down, you should work to own more, when it is up, you should look to trade to increase your productivity. This is the layer underneath the speculation. Also add in that there are growing uses for Bitcoin other than selling for US dollars etc.
I personally try to reduce my living expenses and debt while also trying to collect and create value. If you borrow money, you should look at your cash flow and calculate how long it would take to pay off the debt using your cash flow.