As others have called out, the rewards are real. Let's look at a fairly premium offering, the Chase Sapphire Reserve:
Its annual fee is a seemingly ridiculously-high $550.
However, it automatically offers reimbursement for the first $300 in "travel". The definition of travel is very broad - we're not just talking airplane tickets, this can be taxis, parking lots, trains, buses, highway tolls, hotels, and many other things. And I do mean automatic - I don't even need to log in and select which charges, it just happens.
As such, the annual fee is really $250.
Still too high? Let's say you ignore other specialized perks (reimbursement for TSA Precheck/Global Entry, premium memberships such as Doordash (through 2024) and Lyft (in the past, expired now). Let's ignore real perks such as PRIMARY rental car coverage that means you can decline the pricey loss/damage waiver when renting vehicles and Chase takes care of any claims before your insurance - there have been years when I made most of that $250 back from that single perk alone. Let's just look at cash back.
At an absolute minimum, you're getting 1% back on everything. 1% means 1 Ultimate Reward point, or UR. At an absolute minimum, you can redeem 100UR for $1.00 in straight up cash/statement credit. The actual value is higher (we'll get to that later) but we'll start with this baseline.
You get 3% when dining or travelling (with the same broad definition of "travel" above that probably covers some of your commute to work if you take transit, pay to park, or pay tolls). If you pay attention and use Chase's portals for various travel purchases you can earn 5-10% back (to be honest I'm lazy and almost never bother).
So we're already at the point where depending on your lifestyle, if you put 15-20K on credit cards each year (that's less than $2000 per month) you're probably breaking even - assuming the absolute lowest valuation of points. But why do that? It's trivial to redeem the points at 1.5x for travel by booking through Chase - that is, if you use their portal you can book a $150 hotel room for 10000 UR points. So now we're at 1.5% on everything or 4.5% on travel, and needing to spend only more like $12000-16000 per year to come out even. During the pandemic they made it even easier and let you get reimbursed for various purchases such as restaraunts at that same rate, so even when I wasn't travelling I was getting that full benefit.
If you want to minmax and are flexible on your destination/time, you can transfer UR to various airline/hotel portals and get higher values: https://thepointsguy.com/guide/sweet-spots-chase-ultimate-re...
Did I mention that when you sign up, if you spend enough in the first few months you get a bonus of enough UR to more than make up for the first year or two of fees?
I've had a CSR for quite a few years now (back when I signed up the bonus was 100000UR) and have redeemed the points I've earned each year for more than the annual fee. That is, every year I've had this card I've profited to the tune of hundreds of dollars.
In response to other complaints about spending requirements, the Chase Freedom line earns UR points (without the 3X dining multiplier or the ability to redeem at 1.5X on travel) with no annual fee and no deposit requirement.