Savings interest rates go up and down all the time with the market. If you are getting an above average rate on your savings, do not expect it to stay there indefinitely.
There are a few things at play here. Interest rates have fallen over the last 10 years. If you had asked this question in 2010, everyone would have answered, “Yes, banks start you at a high savings rate and then they drop like a rock.” But it wasn’t necessarily a bait-and-switch tactic; it is simply what the market had done.
In the last couple of years, savings rates have started to creep up again. But we can’t predict what they will do in the future.
Banks do play some marketing tricks in order to lure customers their way. One is the bonus: “Deposit at least $X into a new account, and we will pay $Y after 60 days.” This will give you a nice yield on a portion of your money, and there is nothing wrong with taking advantage of it, but in general this is a one-time payment; don’t expect it to continue in the future.
Another common tactic is to give you an extra high rate if you meet certain conditions on your account. For example, you might get a high rate if you sign up for direct deposit and you have a certain number of debit card transactions. There is almost always a limit in the high rate (for example, 3% on only the first $10,000). In these cases, it is the merchant fees from the debit card transactions that is paying for the increased savings rate. Essentially, you are giving up the rewards that you might receive if you had used a credit card instead of a debit card. The limit on the high interest rate ensures that the bank doesn’t lose money on this. Again, there is nothing wrong with taking advantage of this as long as you are aware of the trade-offs.