The 198 includes the 100$ win, so the original balance was 98.
Part of it is extended playtime, another part is a personal opinion and responsible gaming for me.
When I play one line, it needs to be a game that makes sense for it like free spins and no stacked symbols. In a game like that, you can't win on every line anyways and scatters pay everywhere even though only a single line is active.
This makes the game higher variance too which means the swings are larger, but the maximum win (per line) is still just as great. Ergo, the best way to place a bet on a game with a negative expected return is to make the smallest (or no) wager.
This way, I can't lose enough to care about losing, but when I win it sure as hell feels good.
EDIT: RTG also carries a 50000x line bet win CAP which is independent of the number of lines played, so one line makes more sense too since you'll never hit that on one, IMO