If you're concerned about competition, it's always best to wait until the last possible moment to bid so you have a better chance at controlling if there will be any and how much it will be.

As for why people place bids on plots that already have bids, there are many reasons.

It's one of the very popular plot locations and that location is starting to get multiple bids in every ward.

They're after that specific plot location, not just any plot with the same size house.

The ward is their favorite number.

It was the location of their house on their old world.

They have friends bidding on other houses in the ward and they're trying to be near each other.

Someone did something foolish like publicly say they're calling dibs on X plot and some troll with more gil than empathy and common sense decided they were going to mess with that player (I have seen plenty of that sort of thing in a discord this past week, I hope very much you didn't tell anyone what you were bidding on).

On the positive side, being on Maduin you will be able to get a house even if you don't win tomorrow and you need to wait an extra 9 days. It's better than being on 24 out of 28 of the other NA worlds where pickings are slim this week from the few houses vacated by transferring players and it will likely go back to being no houses in the next lottery.

Let's hope that all that bad RNG in the past means the good RNG has been saving up to grace you at 7:00am PST tomorrow and you will have your house at last.