Trump lost the popular vote by around 3 million votes.
As a statement of fact, this is true.
If by this your intent is to point out how split the country is, great. It shows that there's likely a lot of common ground to draw on, and that Trump by no means has a mandate.
If it's to point out that the discrepancy between the Electoral College and the popular vote is problematic and the process should be amended to fix it, fine. In either case (or both cases), you should say so. Reforming the election process, perhaps even removing the Electoral College is likely a worthwhile goal, and a lot of work needs to be done to make changes like this.
If your intent is to imply that Clinton should be president because the popular vote went to her, that goes to far. The campaigns and GOTV efforts were run understanding how the existing election process with the Electoral College works. If the popular vote determined the outcome of the election, the campaigns and GOTV efforts would have been run differently. Voter behavior would have been different as well. The popular vote result would have likewise been different. That's not to say one candidate or the other would have been elected, that the end result would have been different or the same. Just that the popular vote results would have been different if the campaigns/GOTV were run differently.
Sincerely, you're asking for ideas, and there are other opportunities to vote besides the past presidential elections. If you don't find that suggestion helpful or think it was offered in bad faith, just ignore it. Getting heated or snippy isn't going to do much to encourage others to submit ideas.
Edit to add: And being able to not react reflexively to every perceived slight is itself a good suggestion as it's going to make you more effective in dealing with a lot of the polarization that's out there.
While the previous poster is being a little flippant I don't think he's being totally unhelpful. If you want to send the message you are unhappy with Trump then on top of any protesting you do also make sure you get people to vote, when they can, against his policies. There are mid terms in less than two years so make sure the Republicans who support him take a hammering at the polls.