Thank you very much for all these clarifications. But the strategy you are referring to only works for mutual bettings.
AFAIK most betting platforms only look at the probability of events to occur to fix the odds and don't rely on the amount of bets : doing that would be dangerous for them because it would allow manipulations of the odds.
No, that would be careless
The betting people regularly move the odds, even in the big markets; odds go up and down in Champions League as well. The bookmakers don't even necessarily publish odds according to their models, but they put some "human factor" in as well, i.e. they lower odds for outcomes they expect to have a lot of action on (Liverpool, Barca, Real home win).
All the bookmakers care about is a balanced book, since they don't want to bet and/or take any risk themselves. They have their house edge and will win anyway, if they are doing their job. To get a balanced book (=profit, no matter the odds), they have to adjust the odds frequently, to balance the action. If they need action on away win, they will just increase the odds for away win, if they need action on draw, they will increase odds for draw. When the match starts, they already made their profit in a perfect scenario.
One of the biggest bookmakers in the world, Pinnacle, has automated odds adjustment. I was betting a lot of cycling and this is really a small market. Especially with early odds, after each bet you placed, you could see the odds getting adjusted (odds for my selection went down). This way you can of course manipulate the odds a bit, but bookmakers are not dumb and have measures in place. When odds are published for certain events, the betting limits are small. This way the bookmaker is able to get the market sentiment and can adjust their odds, without having lots of action, in terms of money, on one side already. Once the odds have matured, the betting limits are upped, because there is now a clearer picture of what are the "correct" odds. Near kick-off you then have the highest betting limits, because bookmakers are sure about their odds - the market did all the work for them.
In table tennis (small market), you can even move the odds shortly before matches start. People always go crazy about fixed matches and a few k can move the odds to make it a surebet for certain people like OP.