what s the reason of this big decrease?
Just hang in there, this is still early for this coin and we need more people to find out about it. The new airdrop scheme is going to bring new people and they will be more interested in holding to increase their coin. I think it will bounce back and go up nicely in the coming weeks.
Probably the SegWit adoption in Bitcoin itself.

Yea, I am just wondering myself, what is the advantage of this coin when Bitcoin/Litecoin adopt SegWit with larger blocksizes? Are there features in the pipeline that make Bitcore unique/better than those? I can see that in April Bitcore made lots of sense, but what will happen after August?
That's the point about all cryptocurrencies : what does make LTC better than BTC or BTC better than LTC, ETH better than ETC or EOS, XRM better than ZEC, ZEC better that HUSH / ZEN etc, etc...
If someone has a definitive answer, I would be happy to hear it

1. We dont compare us with different coins. Every coin has its place somewhere.
2. We always wrote, that we are the experiment for bitcoin. Bitcoin was discussing months and years about the update for segwit. But we didnt discuss and did it.
3. The biggest win for us and for you? Share ur ideas in mind with us. All your ideas and contributes for bitcore is a win for everyone. If you have an idea to have faster payments than lightning, so share it with us. Its also up to you.
Greetz
Steve