Hi all,
How do you (personally) decide . . .
Personally?
Bitcoin is ALWAYS a buy.
If I have any funds available that are not already budgeted for some other expense (utilities, debt service, asset acquisition, entertainment, etc), then those extra funds are used to acquire bitcoin as soon as they are available.
In the short term, the bitcoin exchange rate is far too random and unpredictable to ever be able to consistently choose the "right" time to acquire it. Sure, you might get lucky and get it a bit cheaper if you wait, but you also might miss out on some huge growth and never see that lower price again. Since, in my opinion, the long-term direction is for the buying power of bitcoins to increase, any delay only increases the chances of missing out. As such, in the long run, attempting to wait for a better exchange rate will only hurt your overall position.
There is a very strong human tendency to think we see a pattern where one doesn't exist, and to believe we can take advantage of that non-existent pattern for personal gain. This has been demonstrated successfully in experimentation many times. In one example a human is asked to predict which of two events (for example one of two different lights illuminating) will happen next. When the experiment is set up for the events to happen completely randomly, with an 80% probability of one event and a 20% probability of the other, the test subjects believe they see a pattern (which doesn't exist) and they use that pattern to try and occasionally choose the 20% event and do better than 80% success rate. The result is, on average, humans guessing the correct event only about 68% of the time. Meanwhile, when the same experiment is performed with animals (such as rats), they quickly learn (end up trained) to consistently choose the 80% event every time. As such, the animal making the reliable choice to continuously choose the option with the higher long-term average consistently beats the human that is trying to time his decisions against a random process.
Trying to time an unpredictable market is similar. You're going to feel like you can get it right often enough to come out ahead of those that just consistently get what they can when they can. You're going to remember the times when you got it right, and you're going to convince yourself that the times you got it wrong aren't significant or that you can learn from that event how to predict it better next time. If the failures don't devastate you and cause you to quit altogether, then the successes will fool you into thinking you're coming out ahead. Either way, in the end, there's a VERY HIGH probability that you're going to end up with less bitcoin than you could have had if you had simply purchased what you could whenever you could.