Algorithm trading has made many, many billions and is feasible and effective, just not for most ET posters.
As VegasDesert said, the markets change and the algos have to be constantly updated via programmers, I know people who designed algorithmic trading, it worked and then degraded, took 6mths to rebuild and degraded again, at that point they decided better to have a 99% system and make the last 1% discretionary. It was used to setup a crypto fund but they expired it, so far haven't come across anyone who was interested in running a fork due to the algo maintenance problem, a complete drop-in fund launch in a week but someone would have to maintain the algos.
nah. this question is all wrong. and as is necessary, the answers are all over the place. for starters, it is important to define what an algorithm is. and then, algorithmic trading has existed for decades and in all probability generates better results for beginners than discretionary trading. that is because when one knows how to effectively evaluate a strategy one knows then and there whether it will work or not. and people developing algorithms will not trade them if they know they are useles. on the other hand, manual trading will never afford such dramatic knowledge. strategies can be divided into trend following, mean reversion and high frequency trading. they all can be developed and operated with success. all of these strategies are parametric and the first two are heavily dependent on indicators. now, creating programs that will trade based off of geometrical patterns on charts is another different matter altogether. such kind of algorithms could exist but i have never found a way to make any progress in such kind of programs. and they could be nicely profitable but i have no idea how would anyone create such code and which platforms could execute it.