I tried buying and selling such coins. Sometimes I make money. Sometimes I lost money

Some are very suspicious
E dinar
e coin
and func

All has huge trade volume and very bigh spread. If you try to buy or sell for example no body will buy your offer. It's as if somebody is buying and selling among themselves

A few days ago I bought week

https://novaexchange.com/market/LTC_WEEK/

The price went up for a while and crash after I buy. What happened?

Is this a sample of pump and dump?