It’s always a good idea to update your themes, plugins and WordPress installation regularly.
Failing to do so can definitely leave holes open for hackers.
This is especially true for core WordPress updates – it’s a popular system, and people are constantly trying to exploit it.
Luckily, WordPress has an extremely active community who are constantly improving it and fixing any security issues, so if you keep things updated and have decent hosting (GoDaddy shared hosting is always getting hacked in my experience), you should be fine!
Let me know if you have any other questions 🙂