What do the general public understand by miracle?
For one it is a remarkable coincidence bad or good.
For others it is a lucky event - perhaps a win or your arch enemy taking a heart attack while plotting against you.
It may be a natural event that for some reason gets spiritual and religious significance - eg a sunset.
It can be a revelation of God by action or actual verbal communication.
It can be seen as a hint or clue (revelation and sign are too strong here!) that God is present and as an invite to follow him.
It can be seen as a break in the law of nature.
All these things can be seen as intervention by God in some way.
In fact the first one is what has real significance for self-proclaimed miracle believers. They surely know that a coincidence can make it look like a real miracle happened. Plus they are drawn to coincidences anyway - miracles are the style of coincidence that they happen to like the best. For someone who dwells a lot on a miracle like the resurrection of Jesus, even mundane, lucky daily coincidences matter deeply. They see it all as connected, and they deliberately trace those connections, letting the great miracle frame the daily happy strokes of luck. They see it as possible coincidence that they even know of any miracles they value.
Back to the list. I have tried to rank them in order of importance. It is obvious that the tendency is to magical thinking and superstition. Superstition is a form of bigotry for it is a response to fears you have about the universe and its divine maker or makers.
What is the harm in turning a coincidence into an act of God? It leads to cherry-picking. An almost impossibly wondrous bad coincidence is treated as a mere event. Yet a less stunning one is treated as an act of God in some way just because you like it.
Another harm is saying that God plays games and helps you for a thrill. What about people who don't have your luck and who suffer appallingly? No matter what a person says a miracle is, the fact remains that it could be a remarkable coincidence that a supernatural event looks true and is irrefutable. That would mean it is just a natural event that got lucky. So to say x is definitely a supernatural act of God is to automatically say that if it is not then coincidence struck and made it look that way and how will never be known. To imagine you have good luck is an arrogant and dangerous presumption. Superstition is defined by religion as a degradation of religion so it involves bigotry.
Those who turn miracles into signs when they could be mere coincidences end up supporting religious error and get taken advantage of.
A miracle in Christian terms is a call to grave commitment to Jesus or God. What is involved is signing up to being willing to stay true regardless of pressure, persecution and even death at the hands of an evil world. And then there is murderous Satan to worry about. And the other risk is that if Jesus was a false saviour and a saviour is needed then there is the risk of hellfire. Miracles are often taken lightly and as being about spiritual thrills - so that too is superstition. People running after them who care little about being holy are an insult to those who take their call seriously.
If miracles were about learning about God's will and love, receiving his message, a fatal problem arises. It should not take a stunt such as a man appearing after death or any other miracle to get the message across. It is not about the message. Miracles are consistent with man trying to manipulate the people and not divine love reaching down.