I have always supported the method of keep buying the more money you have every x time period instead of going all in all at once.

If you spend $10k all at once then you may end up losing money (you can profit as well) but if you just spend $1k each month for 10 months you can have a decent average, doesn't matter if it goes up or down, you will be closer to whatever the price is right now compared to person who got all in. That is why I keep making bitcoins all the time and spending some of it and saving some of it every single month, I had times where I cashed out at $20k, I had times where I cashed out at $3k, I had times I got paid at $20k, I got times I got paid in $3k.

Hence, it makes like a decent average where you are never too far away from the most recent price.