You can't always tell if a seedling is a weed at first.
When a seed first germinates, it either produces one leaf or two, depending on the type of plant. Those first leaves look very similar on lots of plants, making it difficult to know whether a seedling is a weed or not.
By the time a seedling produces its next lot of leaves, they look like the ones on the mature plant and it's much easier to tell whether the seed is one you planted or if it is an interloper.
When something new germinates in your life, you can't always tell whether it is going to be useful or not. Is it a weed that will need pulling, or is it a plant that will produce fruit?
Sometimes you have to give it a little time.