Odds don't change dramatically in most cases. Even if they do, it won't be very significant. If the odds drop, it means most bettors are betting on a clear favorite, and bookmakers lower the odds because there are already so many people interested. This is normal, and I don't see anything wrong with that. But if everything changes proportionally, then there's cause for concern.
Odds are less noticeable than the spread, in basketball this is what I notice, if the line moves by 1 to 2 points, that is already big, and on moneyline it is also a big change.
But simply looking at the odds and deciding based on your read is not going to give you long-term wins, because the answer is that when there is a line movement, you should investigate the reason behind it. And from there, you decide which side you will take.
You are absolutely right, I have experimented this myself and I ended up wishing I never did, I decided that i don't want to stress myself with analysis and research and so on, that I will always bet on the favorite since that is the team the public have researched on and think they would win the match.
My thought was that even if the favorites loses, it would be a few, that is that the majority of the favorites will always win and that will make me stay in profit if I can be betting with the same amount of money and manage to win more bets than I lose, this seemed like a perfect plan.
Long story short, I began betting and over time, I was losing far more than I was winning, at a point, I was forced to stop and start doing my own analysis and research before placing a bet and this was when I started seeing some improvement, a prove that the public isn't always right.