Isn't it easier to hack into such addresses containing unique brand names in a public address?
Not if it was generated properly, as ETFbitcoin has pointed out above.
A private key is just a random number between 1 and (almost) 2
256. I pick a random number in that range, and it gives me a random looking address. You have a 1 in 2
256 chance (i.e. completely impossible) to guess my private key.
Now, let's say I want a vanity address. I take the same private key I just generated above, and I add one to it. I check the address it generates. It doesn't give me my desired vanity address. So I add one again, and check the new address. Still not a match. So I do it again. And again. And again. Adding one each time and checking the new address. Vanity generator software will do this millions of times a second. Eventually we find an address which matches.*
What does an attacker know when they see a vanity address? They know that I started a random private key, and I added an unknown number of 1s until I reached a new private key. So an unknown plus another unknown to reach a third unknown. This obviously tells them nothing useful about my private key, and so provides no additional attack surface over any other private key.
*This is a simplified explanation which does not touch on symmetry and endomorphism, but the premise is the same.