The stronger you are the less you have to rely on balance when doing a handstand. Instead of searching for this golden point where things magically align you can simply force your handstand to work. You can demand to stay up. 

On the other hand if you are confident in your ability you will be less likely to make mistakes leading you to feel stronger and to perform better.
While strength and confidence clearly are not the same thing when it comes to handstands they seem to be rather closely related. Let’s have a more in detail look at how they come together when training and performing handstands.

Starting with strength and stating the obvious first. The stronger you are the easier it is to make your handstand work as you do not have to rely on form and technique. If you fall you don’t necessarily fall all the way down. Instead you just dip down, bend your arms and fight back up.

You can leave lots of room for error as you know that they simply won’t do anything to you. 

Not so obvious is how strength comes into play when learning to hand balance. When first getting upside down your form is probably rather bad and you do not have any feeling for balance. The only way to hold a handstand that is not well aligned is by being strong. The more your technique and form improves the easier your handstand becomes and the less strength you need to stay upside down.
Now in order to improve technique and alignment you have to train. The stronger you are the more you can train. It is that simple. The stronger you are the longer you can stay up in basic handstand exercises building coordination, awareness and work on finding your personal balance point. 

So we have established and agreed on that strength is confidence. Let’s see how exactly Confidence is also strength. This is better understood by looking at it from a different side.

Self doubt is weakness.

Personally I struggle with this one quite a bit. When I get up into a handstand and scenarios of how this handstand could possibly go wrong fly though my head you can be pretty sure that I will not nail it and probably mess up. This is why for me it is crazy important that I am very focused when training and actually only train handstands when I feel good. At this point I am not trying to learn new shapes or combinations. I am just trying to perfect my performance. If I have a training where I fall or come down a lot I will start to doubt myself on stage and mess up there as well.

As long as you have acquired skill and strength to do a handstand the more you believe in yourself the more likely your handstand will be stable and strong