Before trying it myself, I was somewhat skeptical when reading about how these indicators don't work well. The overlays on charts always looked like good buy/sell indicators, so I didn't really understand why they couldn't make for a good algorithm. Only after trying it myself did I gain insight as to why they don't actually work so well.
I guess it's better to learn the hard way than to learn the hard-and-painful way with real money ;)
Would you care to elaborate on which indicators you tried, and what happened?
There are at least two other important considerations apart from the indicator itself: how to actually execute effectively with limited funds (when your trigger fires, do you trade everything you can, only a certain percentage, or some variable amount based on technical factors? - that's an entirely separate algorithmic rabbit hole); and even if you do find a good algorithm and it performs great in backtesting historical data, it's almost always harder to achieve the same results in real market conditions (it's difficult to simulate the spread and dynamics of limited market depth).
It is one of the core foundations that underpin up modern finance (something that Bitcoin advocates would be keen to learn about...) - see also [Efficient Market Hypothesis](https://en.wikipedia.org/wiki/Efficient-market_hypothesis), [Modigliani and Miller Capital Structure Theory](https://en.wikipedia.org/wiki/Modigliani%E2%80%93Miller_theo...), or the [Modern Portfolio Theory](https://en.wikipedia.org/wiki/Modern_portfolio_theory).
In short, TA has refuted time and time again. It's complete garbage used only by amatures.
I don't think TA is complete garbage, but I agree it's not a fundamental.