You are right to hold some skepticism around trading bots, the truth is that bots can be very effective but there is a catch, if you do not know how to trade manually then there is little hope that you will make any money even with a trading bot, you need to know how to trade because if you do not then it is going to be impossible for you to actually know if the strategy that the bot is using is profitable or not, so if you were to code a bad strategy into the bot the only thing it will do is to lose money for you at an alarming speed.
That's what I always say to my friends who consider using trading bots, if they don't have any experience trading or they don't know how to do a trade themselves that generates profit then how will they generate that profit in a bot that only follows your instructions, a bot will only be as good as it's owner and the specifications that that person has added to the bot.
If they use trading bots without knowledge about trading, it is absolutely that they just waste their money and time. That is really not advisable for them and instead of learning how to use trading bots, they'd rather help themselves to learn first and focus on improving their knowledge and skill as this will not just give them the passive results but this helps them to realize that trading is not an easy job.
Maybe I could say that trading bot is also good but have to accept that this is not meant for everyone.