Never loosing indicators(?)

Hi redditors,

I have a stupid question with a standard obvious text-book answer goes like "are you dumb?." But I am curious anyway about your creative ways of saying it.

I have a friend who I know for a long time and he is interested in stock market for the past few years. He is looking for indicators and trying to apply them to different indicies, shares, CFDs etc. Recently his claim was that he found never loosing indicators. His argument is that those indicators work with 5mins intervals on some assets and 1 hour in some others. They involve having put and call options depending on what indicators signal with the current market value, volume trend etc.

He makes all the hyper-parameter optimization using past data and further proposes that, in 1 to 2 year time windows, he could have made 40%, 50% and even 100% net profits using these indicators including comissions etc. When we ask why there is that much gain but absolutely no risks, his argument is okey in the long run if not making 50% 100% profit then 25% 30% is still free money that one should get.

I am a novice trader who is learning and enjoying it and consider it as securing my today savings' purchasing power for the future. Besides I have my day job and I find it too stressful to make high frequency trades. Even in slow pace, I think it is sometimes stressful. All things put asside, when I check public funds managed by pros and their performances, they don't make 50% 100% net profits every year. If this is something that obvious such that one guy realize at home looking at the graphs, then why not everybody is making this as their only job? Paradoxically, if everybody applies the same and simple tactic, then no one could have won. Anyway...

What would you guys tell your friends, if you were in my shoes?