Above is the capture from the Econometrics slide from "Hill,Griths and Lim (2018) Principles of Econometrics".
I have no problem the see the blue font sentence separately, it's all about the numerator and denominator issues. But, if I think deeply about its intuitions, it bugs me.
The first blue sentence could interpret as more coverage of $x_i$ can reduce the variance
then I expand the equation, larger $\sum(x_i-\bar{x})^2=\sum x_i^2-n\bar{x}^2$ means Larger the value of$\sum x_i^2$. It's reduce variance, and this contradict to second blue sentence Clearly second blue is right, so what's go wrong with my reasoning about the larger $\sum x_i^2$ .
Please enlighten me, Thank you so much