I'm new around in the crypto world, but fascinated! Want to start mining XMR but wonder if the reward stays the same. Does it maybe, as with BTC, become less because of the bigger blockchain? Or does the reward of let's say 0,03 XMR per day get less when the value of XMR becomes more (compared to USD)? Thanks for your feedback!
Want to start mining XMR but wonder if the reward stays the same.
No. It's changing according to emission schedule. If you're asking about how much an individual miner could be getting - on average, he'll get a proportional amount of his hashrate. If he's solo mining, this means he could be mining for a long time before he ever receives anything. That's why people pool their efforts together, and split the reward once they win it. That's called pool mining.
Does it maybe, as with BTC, become less because of the bigger blockchain?
Size of the blockchain has nothing to do with that. Reward is tied only to blockchain age, as per emission schedule. Technically, it's tied to amount of monero currently in circulation, but effectively it's as if it's tied to age.
Or does the reward of let's say 0,03 XMR per day get less when the value of XMR becomes more (compared to USD)?
Monero reward (in XMR) will keep reducing as per emission schedule. Somewhere in 2023, it will get to 0.6XMR (per 2-min block) and stay like that forever. This is known as "tail emission" (1, 2). Thing is, as more miners enter the space, it will be shared among more and more miners so each individual miner will receive less XMR. However, they'll probably be receiving a more-less constant amount of USD, governed by hardware efficiency and cost of electricity.
Mining works like a scratch-lottery. The stronger CPU you have, the more tickets you're able to purchase per 2-min round. Note that the round is closed only once a winning ticket is found, regardless of time. If winning tickets are found too fast, criteria for winning becomes more strict and if too slow, then it's relaxed. It's called "difficulty adjustment". Tickets cost eletricity. Since alone you have low chance of winning, you pool your efforts with a bunch of people to increase the chance of someone from your group winning. Then, you split the reward according to how much "tickets" each of you contributed.