I read on here in another post that a good rule of thumb is 20-25 times gross income. This is the first time I've heard that and I consider myself fairly well read and financially savvy. Anyway, just curious if that has an age constraint? i.e. if you're 50 and have 20-25 times gross income, great, definitely FIRE. or if you're 35 and have the 25x, nope you'll be FIRE too long, back to work for you. Also, if you can recommend reading material that would be great. Thanks.