"The stock market is currently a bubble!" If it takes 10 years for it to fall 30% in one month, you are right it is a bubble, just really, really early. If it falls next week you are right.
In either case, you calling it a bubble added no value.
If you are going to say we are in a bubble, then there must actually be a real bubble at the time, not at some future hypothetical time.
At any point where prices trend significantly upward, beyond historical cyclical patterns, there is a potential for a bubble. Whether that trend is indicative of a permanent market shift or whether it is a temporary phenomena where prices will revert to the mean afterwards is what decides whether or not there was a bubble. Whether you are at the start of a bubble or near the end of a bubble doesn't change whether or not it's a bubble.