Why is that when you, the bank, or whomever checks your credit score, it goes down?

It does not go down when you check it yourself.

It does not go down when someone else checks it on their own.

It goes down only if someone else checked it because you applied for something.

Credit score should not be solely about how well you have paid off your credit in the past.  It is about how well you are likely to pay it off in the future.

If you are doing a lot of applying because you are desperate to borrow money, that means that you are having financial problems and are likely to have difficulty paying back the money.

You do not want someone's score being actively checked, because that means that they are actively applying.

Your score does not go down when you check it.

It goes down when others check it because tit's usually an indication that you are taking more credit. 

I believe that indicates that you are anticipating using more of your credit to buy something. 

Lenders only do a hard inquiry when you've applied for  credit.   Applying for more credit temporarily lowers your score. 

My credit union will show my score when I sign into online banking.  It doesn't affect my score at all.

"You’d think you’d want someone to be actively checking their credit score?"   Why?   My score is a reflection of my behavior and I already know what my behavior is.    Credit scores are not surprises. 

Each time you authorize someone other than yourself, such as a lender, to check your credit history, a hard inquiry is recorded on your credit report and could slightly affect your score for up to two years.

As your credit profile matures, it's natural to accumulate hard inquiries. But if you apply for too much credit in a short period of time, it can negatively impact your scores and affect the likelihood that lenders will approve you for new credit.

Depending on how many inquiries you already have, a new hard inquiry could cause your score to drop, but potentially only for a short period of time. And any effect on your credit score should disappear in about one year.