Hi Nina, Swing traders not necessary needs to have strong patience and nerves. More often, they do not have time to trade on small timeframes and uses 4h, or Daily or weekly charts and they are waiting the big moves.
Also, they might found that this type of trading works for them better then whole day sitting in front of the PC.
In regards to swaps, some FX pairs does not have really big swap charges and even to hold position for long period, the price movement may brings much more profit / or lose compared with swap charges.
Indeed there are some TRY and ZAR pairs where the charges and incomes from the swap are significant if you hold the pair longer term and those figures my affect over the end result :)