You can have fun "playing" in the beta, while Testers do their "job" at finding bugs... it's not hard to do both.

You really have to let the bugs come to you and not ignore them like it's a little thing. A little thing to you can be gamebreaking for a lot of people.

Me: Running around killing monsters ( Fun part)
Me: Notices that this monsters won't die at zero HP/Notices this monsters HP won't drop below 50%. ( Doing your job part).
Me: Reports it in for SE to fix this issue ( if I don't send it in there's a possibility it can effect launch.

You can have fun in Beta, no one is saying to not have "fun". but you also have to do your job, If you spot ANY bugs, report them ASAP.