<p>I assure you, there is no contradiction. Those who make it to top schools with publications have level of talent/energy/dedication well above yours, and they are able to excel academically while working at the labs. Apparently, this is not the case in your case. And given that, in your particular case, if you have to choose between lab experience and good grades, it’s better to choose good grades.</p>
<p>I know that you think that your getting bad grades has nothing to do with your spending time at the lab, but it does, and it will be duly noted by the grad school admission committees.</p>