all those fancy thing are only good to makes you lose money, i prefer to store them in my desktop sincerly..
I don't understand how these types of things are safe when the person who makes them has access to your private keys.
No they don't. Only you have access to your private key, you are the one who assembles the letters in order, not the manufacturer.
they could brute force those arrangement?
There's nothing to brute force, they never get to know your key. Look at it this way: they sell you a pencil (made of steel) with witch you write down your key. What is written down doesn't know anyone but you, and it is not literally a pencil but a set of numbers and letters to arrange them as you want.
It's amazing how people misunderstand what is this all about, they are obviously not doing a good job explaining their product.