title: pip/python: normal site-packages is not writeable
body: <p>I have a new Macbook - a user installed it, and then I installed a new user (mine), granted admin privileges and deleted the old one. I am on OS Catalina.</p>
  <p>Since the installation I've been having several permission problems.
  VSCode can't find Jupyter Notebook, <code>pip</code> installs packages at <code>~/Library/Python/3.7/site-packages</code>.</p>
  <p>When I do <code>which python3</code> I get <code>usr/bin/python3</code>.
  When I do <code>pip3 install &lt;package&gt;</code> I get: <code>Defaulting to user installation because normal site-packages is not writeable</code> And then it says it has already been installed, even though I can't access it when I do <code>import &lt;package&gt;</code>.</p>
  <p>It's seems clear that this is a permission problem, <code>pip</code> can't install to the &quot;base&quot; python, and them <code>python</code> can't find what I've installed into <code>~/Library/Python/3.7/site-packages</code>.</p>
  <p>I've tried reinstalling the OS, but since I haven't done a clean install, it didn't change anything.
  What am I missing?
  How exactly can I fix permissions? Where do I <em>want</em> packages to be installed (<code>venv</code> sure, but some packages I want global (like <code>jupyter</code>).</p>