According to Wikipedia:
You might think you aren’t collecting anyone’s personal data, but it’s quite likely that your website tech is doing so without your knowledge.
The answer is yes, you really do need one!
1. Its a legal requirement
3. Your visitors care about their privacy
1. The most expensive but most reliable way – hire a lawyer or legal professional.
3. There are a few WordPress Plugins that will generate legal terms. Be aware of the originating country of these plugins to make sure it applies to you. Again, get it reviewed by a lawyer.
2 plugins that I have used you might want to consider
You may not rely upon this information as legal advice. Legal information is not the same as legal advice and requirements and laws vary by region and country. Always consult with a lawyer or legal expert.