I use bots for my own style of mostly mid-term trades, but if you were to try to perform arbitrage, you'd have best success with using bots. It's very hard to do manually considering it's already highly automated, and with certain exchanges where you might see arbitrage opportunities, there may be strings attached that you aren't aware of like added fees or the exchange simply being unreliable.
While it's true that bots could potentially malfunction and make you lose some money, there's plenty of safeguards in most bots like stop losses to minimize the risk of anything like this happening. I've been running Gunbot for many months without any major issues.
If you're looking for a more reputable arbitrage bot option than what you might be getting offered, a number of authorized Gunbot resellers such as crwth offer it for 0.95
BTC. Here's one such thread (
click for link) where you can find information on how to purchase it.