Slight modification is required in the configuration for this work:

metadata:
  name: vbox
  labels:
    app: vbox
spec:
  selector:
    matchLabels:
      app: vbox
  template:
    metadata:
      labels:
        app: vbox
    spec:
      securityContext:
        runAsUser: 0
      containers:
      - name: vbox-vm
        image: my-vb
        imagePullPolicy: 'Always'
        securityContext:  # << added
          privileged: true

        ports:
        - containerPort: 6666

        volumeMounts:
        - mountPath: /root/img.vdi
          name: img-vdi

        - mountPath: /dev/vboxdrv
          name: vboxdrv

      volumes:
      - name: img-vdi
        hostPath:
          path: /root/img.vdi
          type: File

      - name: vboxdrv
        hostPath:
          path: /dev/vboxdrv
          type: CharDevice

To be able to run privileged containers you'll need to have:

• kube-apiserver running with --allow-privileged
• kubelet (all hosts that might have this container) running with --allow-privileged=true

See more at https://kubernetes.io/docs/concepts/workloads/pods/pod/#privileged-mode-for-pod-containers

Once it works do it properly via PodSecurityPolicy