DDoS attacks are usually volumetric attack. Send more bits than the pipe the website has to the internet.
To combat this you need to buy enough pipes to the internet for your regular internet traffic, as well as an extra 500 Gbps or so. That is a lot of unused bandwidth to be paying for every month. Then once the packets arrive at your datacenter you still need to buy dedicated appliances to scrub out the bad and let the good flow.
Google is constantly under attack, but their normal daily traffic volume (multiple Tbps) is large enough that just the extra capacity they keep on hand to deal with traffic spikes the World Cup or a popular YouTube video is larger than what most attackers can muster.
To combat this you need to buy enough pipes to the internet for your regular internet traffic, as well as an extra 500 Gbps or so. That is a lot of unused bandwidth to be paying for every month. Then once the packets arrive at your datacenter you still need to buy dedicated appliances to scrub out the bad and let the good flow.
Google is constantly under attack, but their normal daily traffic volume (multiple Tbps) is large enough that just the extra capacity they keep on hand to deal with traffic spikes the World Cup or a popular YouTube video is larger than what most attackers can muster.