Do you see side bets like the way to win some money, or to loose it? Real money, play money, no matter.
If you're talking about the side bets that some
casinos offer where you can bet on the flop color being red or black, I stay away because there is a vig (premium) they charge on these bets.
If it is just between friends then the
odds will be fair but I still avoid it because it takes away from my focus on the main game which should be my main source of income.
The only time as a pro I would want to engage in a sidebet, is if the player I'm making the bet with will be more distracted from it than I would thereby giving me an edge or net gain.
Some people like the extra action and gamble but personally I find the less gamble I have the better I do, because the less gamble, the more focus I have on simply playing well.
And playing well generates profits!!!