Is buying minecraft safe?

It is safe if you buy it form the official website, (minecraft.net)
as minecraft does not charge more than the price to buy it, like most websites. The only way your not safe is if someone installed malware or other viruses that keep track of everything you send to steal your information, which happens if you download things illigaly or click on those surveys or other too good to be true offers(free expensive electronis included). You are not guaranteed to have or get viruses from these, many are just forcing you to buy stuff to get what they say is free, but some do send viruses. The best bet is to run any antivirus and other software like that you have before hand, then hope(if you ran them, odds are extreamly high your safe). No transaction over the internet is 100% safe, but far more often than not, if its a official website, your information will not be misused.

free software that helps with anti-virus and other stuff if you don't have any or want more
SuperAntiSpyware
MalwareBytes AntiMalware.
these 2 are free that i use alot. If you have to pay for one of them, your getting ripped off as they are free for the basic services of removing all scanned malware and viruses.

*Facepalm*

No they, won't take your credit card and all your money. You just pay for minecraft, you download it, they give you an account to log in on the Minecraft launcher, and there, you have Minecraft.

TL;DR Yes.