There is some truth to what you say, especially when you differentiate between sports betting and casino games. However, there are some points that need to be addressed.
First, “there is no such thing as a smart strategy” — those who say this usually mean games of chance (such as roulette, slots, dice, etc.). In such games, no amount of smart or analytical strategy can really bring long-term profits, because mathematically you will lose — the house always wins.

But the way you present the ‘value betting’ strategy in sports betting is absolutely logical.

-The basis of this strategy is: finding errors in the bookmakers’ odds, placing bets that are mathematically profitable.
-It is basically like finding ‘undervalued stocks’ in the stock market — if you can consistently get the analysis right, you are betting at a positive Expected Value . It can be profitable in the long run.

But remember this:

-Just because you say “strategy” in sports betting doesn’t guarantee you’ll win.
-It’s a skill-based process of discipline, data analysis, money management — all in all. There’s no room for emotion here.

And as you mentioned in the Martingale strategy in casino games — it’s a differential “loss recovery method,” but it’s not sustainable because of the game’s inherent negative expectations. You might get lucky once or twice, but the risk of wiping out your bankroll in the long run is much higher.