I'm old. You're right, it's an old person's game. Why? Because it's difficult & time consuming to get proficient at & practically no one today under 50 wants to devote the time & effort it takes to become so. So quality players are slowly dying off. Sorta like becoming good at handicapping horse races. Bridge was a much bigger deal (PI) from 1930's to 80's.
It's fairly easy to get the basics & play social bridge that way. But as I said, being proficient - willing to play for $ or being successful at duplicate bridge - winning ACBL points - is another matter. All kinds of classes are given & books written.
I play duplicate bridge - can hardly tolerate social bridge - mainly at the Northern Ky Bridge Club in Erlanger, typically 3x/wk in 3.0 - 3.5 hr sessions. It's part of the American Contract Bridge League (ACBL). I rate myself as a better than average club player, and average regional tourney player, and have no chance against experts EXCEPT: it's not totally predictable and on occasion average players can upset world grand masters. Masters sometimes play against peons in club games.
The duplicate Bridge Club of Lexington is on Lansdowne Dr & is also part of ACBL. I've played there several times. Nice facility. Clubs charge between $7 (NKBC) & $20 (NYC/Palm Beach)/session to cover facilities, cards, tables, snacks, equipment, & usually the game director's fee. Duplicate bridge has very detailed & rather strict "laws" and the director has to deal with player screwups of all kinds. I'm a just beyond beginner into novice director quality & do it for free.
Social bridge is typically a one table game, meaning you play against the same pair the entire session. Each hand is dealt after shuffling, thus with no control over who gets good cards or not & that thus affects the winner.
In duplicate bridge you can have from 5 to hundreds of opponents depending on the size of the game. In most club games you have between 5 & 10 opponents. All hands are pre-dealt and numbered before the session begins & are placed in 4-slotted "boards". Players have a fixed position - North/South/East/West - & same partner. You remove the cards & bid & play the hand. To keeps cards from being mixed up, you place played cards in front of you & return them to the same board slot when the hand is complete.
For example, if there nine opponents, you typically play three of the boards against each of the nine opponents or 27 boards/hands by EW pairs moving tables & boards moving. In fact, you're not really scoring against the players you play, but against the other players in your same direction as YOU ALL PLAY THE SAME HANDS !! At the end of the game, your score is compared against all the other pairs in your direction, EW or NS, to determine the winner. Also, most sets of hands are computer dealt & printouts are available after the session so you can see how you (typically) screwed up - miss-bid and/or misplayed.
Clearly I enjoy it. While I knew social bridge in my 20's, didn't play much & didn't get into duplicate till near 50. BTW, one of the best 100 or so young duplicate players in the country plays & directs at the Lex club. He's from NKBC & attends UK.