Dissent is a patriotic act, when you are trying to make a nation better, or prevent it from becoming worse. For why protest matters, see Eugene Robinson and Sarah Jaffe. Practically speaking, protest by itself does not achieve a goal, but as Jaffe argues, protest is a vital part of democracy, and is way for those who feel strongly to discover that they are not alone. It is a first step before later, practical actions (see Indivisible, the ACLU, the Brennan Center, Evan McMullin, and other links in the right sidebar).
Needless to say, the best outcome would be if the worst fears expressed about the new Administration never came to pass. It could happen if the press faces up to the threat they face (see Josh Marshall), if progressives rise to the occasion (see Indivisible), and if conservatives of conscience make it clear that many issues, such as equal justice for all and freedom of expression, transcend party (see Evan McMullin). If these three groups succeed, it would be a testament to Churchill’s statement that Americans can be relied upon to do the right thing, after trying all the alternatives.
In the meantime, here are some of the fears: essays by Masha Gessen, Timothy Snyder, Aleksandar Hemon, and Sarah Kendzior. Krugman points out that the incoming administration isn’t ready, which may slow things a bit and suggests a different, perhaps less threatening, kind of failure. My analysis of President Trump’s record-low approval ratings suggests a surprisingly weak presidency.