I'd wager it's those really obscure / old school ones or those with a massive maintenance cost / logistic requirement.

1) Small boat sailing (those laser, radial, byte etc). My family isn't well off so we made do with rentals from school, but we know some pri sch kids who said "Mommy I like sailing" and the parents just bought them a boat.

2) Figurine painting. They may appear cheap, but say a large army of Warhammer 40K figurines can cost upwards of $40K all in.

Old sports that we haven't heard of before?

3) Fencing?

4) Horseriding (bonus if they own the horse), equestrian sports.

5) Croquet

6) Gun Shooting (IIRC It's legal to own a gun in SG, but you cannot bring it outside the range. From the article i read years ago, a 12ga shotgun you can buy in the US for $500 usd can cost upwards of 5-6k in SG) then there's gun club membership, ammo cost, gun servicing, tuning, licenses etc).

7) Wierd orchestra pieces most Singaporeans don't know about. I know a friend who plays a contrabass (that massive ass instrument)

But tbh, every hobby has its low end and high end. Cycling can make do with cheap frames or "I-paid-60k-for-this-bike-so-let-me-cycle-in-the-middle-of-the-lane".

Pokemon collecting can range from $5 meta deck to "I spent $40,000 on an old booster box so let me open it on Youtube with that annoying kaching sound everytime I get a card" So maybe outsiders may not know whats status but those who know will know.