Give day-traders, swing traders and long term traders the same capital and the same trading system (assuming the strategy works on every time frame) and day-traders will ALWAYS make more (much more) money at the end of the year.
I believe this is true not only because day traders will trade their system more often, but
also because the Forex market is notorious for forming patterns consisting of surges and pullbacks.
Consequently, a swing trader and especially a position trader is going to be repeatedly forced to stand by helplessly as s/he watches his or positions vacillate in and out of profit territory over and over again, whereas a nimble day trader can enter positions with each pullback and pocket gains with each surge, thereby accumulating compounded profits by executing overlapping trades.
For instance, in the example below, a day trader could buy the asset each time the candlesticks begin to form a trough below the ascending yellow moving average and sell it each time they begin to form a crest above it, thereby milking the maximum amount of return from the Forex pair while still within the same general region.
Moreover, the day trader will have made his or her returns a reality three to five times, whereas whatever gains the swing or position trader is currently enjoying are merely paper profits and
could disappear if the market should decide to reverse direction.