If evolution is real, why are scientists worried about the extinction of animals

Because we hate to see them go.

Certainly it happens naturally over millions of years,
but a lot of what we are actually seeing is our fault . . .

MILLIONS of species of animal have become extinct in the history of evolution - The dodo being a common example. The reason animals become extinct is because they fail to adapt to new environments. For example, many species of cat (or felidae, if you like) are struggling to survive as their ideal habitats are being destroyed by humans - and because they are unable to adapt to other conditions, they simply die off. This is also the reason humans and insects thrive so well - our unmatched ability to adapt to new environments.

First, you do realize that as a part of evolution, many species go extinct, right? They don't all just magically evolve to survive. You do understand that, right? Because if you don't, you really shouldn't be opening your mouth on the subject of evolution.

Second, while extinctions are natural, they may not be to our advantage. So, your question amounts to asking "if death is a real thing, then why do we have doctors?" Loss of biodiversity can cause disruptions of ecosystems that have implications for human health and welfare. As such, we want to avoid them, even if they're natural.

Why would they not be? Evolution takes millions of years and it can never recreate an animal that has gone extinct. Once we lose an animal it is gone forever.
When you take something out of an ecosystem you cannot predict what the results will be, so it's best not to take things out. And aside from that we have a moral duty to preserve the rich variety of life on the planet for future generations.

natural evolution is ok but as each species is dependent on the ones below in the food/evolution chain if species begin to become extinct before they should it could get to the point where mass extinctions become common like dominos falling and this will probably be our fault

because they are not the same scientists the believe in evolution

Because variety is a nice thing to have in life. Evolution can be messy.

because it can disrupt the ecosystem and right now there are many endangered species