If you read tourism news regularly, you will know that, yes, they prefer Chinese travellers who come here for only one week, do the trip to the 'island', perhaps to Wat Phra Keaw, then spend the rest of their baht at Big C for a suitcase full of snacks, not to be seen here ever again. Anyone staying longer than 10 days, or who 'comes too often' must be a "criminal"...
And yes, 'big money' now, rather than 'very big money' over a longer time span is deeply ingrained in the Thai psyche.
Still, people continue to come in large numbers, so it works out well for them.